CCIE EXAM POLICY (AS PER CISCO GUIDELINE )
•Age Requirements
In compliance with the Cisco Privacy Policy, age requirements for Cisco certification are as follows:
• Underage Minors are children under 13 who may not test or receive certification even w/parental consent
Minors are individuals between 13–17 years of age who may test and receive certification w/parental consent
Individuals 18 years or older are eligible for certification without any age-related restriction
For more information, please refer to the Cisco Career Certification and Confidentiality Agreement.
Conduct
Candidates must agree they will not compromise the integrity or confidentiality of any Cisco certification exam or certification program. Prohibited actions are described in the Cisco Career Certifications and Confidentiality Agreement. Remedies for violating the policy can include a lifetime ban on all future exams and voiding of all previous certifications.
Confidentiality
The questions and answers of the certification exams are the exclusive and confidential property of Cisco and are protected by Cisco's intellectual property rights. Candidates taking Cisco exams must agree they have read and will abide by the terms and conditions of the Cisco Career Certifications and Confidentiality Agreement before beginning each exam.
Correspondence
All official correspondence to certified CCIEs and candidates is sent to the email address in the CCIE database. This database is SEPARATE from the Cisco customer database. Changing an email address in the Cisco customer database does not automatically update the CCIE database. CCIEs and candidates must keep their CCIE email address updated in order to ensure they received all official correspondence.
Exam Discounts, Vouchers and Promotional Codes
Neither Cisco nor Pearson VUE, its primary test delivery partner, guarantees the authenticity of discount vouchers or promotional codes that are obtained from any individuals or entities other than Pearson VUE.
Individuals or Cisco affiliated partners who use certifications discount vouchers or promotional codes that are fraudulent or otherwise obtained from an unauthorized source (including legitimate vouchers for attempted re-use) may risk up to and including a lifetime ban on all future exams, the nullification of all previous certifications or other program sanctions at the discretion of Cisco. Cisco will not compensate candidates for fraudulent vouchers or vouchers obtained from an unauthorized source.
Exam Violations
Disclosure of test content is strictly prohibited. Please report any suspicious activity as described in Cisco's Exam Violation Rules.
Lab Exam: Double Booking
CCIE candidates are allowed to schedule only a single CCIE lab exam date at any location for each CCIE track. Double booking for lab exams in the same track, at either the same location or different locations, is not permitted by the database. Candidates will be allowed to simultaneously schedule lab exams for different tracks.
Lab Exam: Exam Rules
Candidates for the CCIE written exam or lab exam are not allowed to bring anything into the exam room or take anything out. This includes, but is not limited to: notes, documentation, watches, laptops, keyboards, pagers, PDAs, and mobile phones. DO NOT confer or consult with anyone about the exam while taking the exam or after the exam is completed. During an exam, you may only discuss your exam with the lab engineer.
Lab Exam: Payment
Price not confirmed and is subject to change until full payment is made.
Types. Lab sites in China and Japan will only accept payment via wire transfer. All other locations accept online credit card payment (American Express, Visa, Mastercard, or Eurocard) See “Lab Exam: Scheduling and Payment” for details. You are responsible for any fees your financial institution may charge to complete the payment transaction.
Due Date. Full payment must be received at least 90 days before the lab exam date. Only one e-mail notice is sent as a payment reminder. Payments generally take one to seven business days to process, so be sure to initiate payment in advance of the due date. It is important that if payment will be made by wire transfer, that the payment is scheduled well in advance to prevent the lab date being dropped. Exams for which payment is not received by the due date will be automatically dropped from the schedule. If you still wish to take the lab, you must rebook the exam online and complete your payment. There is no guarantee that your original date will still be available once it has been dropped for non-payment. If you book an exam for a date less than 90 days away, you must complete payment on the day you book the exam or the registration cannot be submitted. Candidates are ultimately responsible for making the lab payment in a timely manner and Cisco will not be held liable for any candidates automatically dropped due to non-payment.
Processing. Credit card payments entered into the system will be processed on the payment due date, exactly 90 days prior to your lab date, as will invoices for all payment types. Be sure the company name, invoicing address and email address are complete and accurate to ensure proper delivery of your invoice. No invoices will be generated before the lab exam due date.
Lab Exam: Rescheduling, Canceling and Postponing
Prior to Due Date. Cancellations or changes to the exam date, location, or track must be made prior to the payment due date--90 days before the scheduled lab date. To make any changes, you must log into the Lab Scheduling tool and drop your current lab. Then you can reschedule according to preferred date, location and track. You may book an exam for a date less than 90 days away, if you complete payment on the day you book the exam.
If you need to cancel an exam before the due date, and paid via a wire transfer that has already cleared, you are eligible for a full refund by requesting support via the Certifications Online Support tool.
After Due Date. Changes and cancellations are not permitted after the payment due date--90 days prior to the scheduled lab date--and no refunds will be issued. If you are not able to attend your scheduled lab date, contact support to let them know the lab seat will not be used. You will still forfeit your payment, but you will be allowed to book another exam date immediately. If you do not contact support, you will be marked as a "no show" for the exam and be barred from booking another exam for 30 days.
Candidates Requiring Visas. If you require a visa to attend your lab exam, it is strongly recommended you apply 10-12 weeks before your lab date. Candidates who fail to obtain required visas will still be bound by these cancellation policies and must cancel their lab exam before the payment due date to be eligible for a full refund. For more information in requesting a CCIE Invitation Letter, please visit our CCIE: Invitation Letter (Entrance Visa) Instant Answer.
Lab Exam: Reevaluation of Lab Results
Exam results appeals are available for the routing and switching, security, and service provider technology tracks. Only exams with potential to change from fail to pass will have the option to request an appeal, based on years of historical data. Appeals are not available for the voice or storage tracks due to equipment limitations.
An appeal consists of a second proctor loading your configurations into a rack to recreate the test and re-score the entire exam. This process takes up to three weeks after receipt of payment. Only one appeal per lab attempt is permitted.
The result of the appeal is a confirmation of the existing fail or an update to a pass.
Payment Terms
Make your request within 14 days following your exam date by using the "Request for Reread" link next to your lab record. Each appeal costs $250.00 USD plus any applicable local taxes. Payment is made online via credit card and your card will be charged upon receipt of the request. You may not cancel the appeal request once the process has been initiated. Refunds are given only when results change from fail to pass.
Lab Exam: Retakes
All candidates must wait 30 days between CCIE lab attempts. Please note the 30 days starts from the day after a failed lab exam.
Lab Exam: Scoring
You must obtain an overall score of at least 80% to pass the lab exam. You can view your lab exam results online (login required), usually within 48 hours. Results are Pass/Fail and failing score reports indicate major topic areas where additional study and preparation may be useful.
Lab Exam: Start Times
Start times for exams are indicated in email can also found on the web page associated with each lab location (for a list, see Lab Exam Locations). Pleaseverify your email address in your candidate profile so we can notify you of any changes. If you have any questions about the start time of your exam, please contact CCIE customer support through the Certifications Online Support tool . If you arrive more than two hours after the start of your exam, you will not be allowed to start. If you arrive less than two hours late, you will be allowed to start but you must finish with the rest of the group.
Logo Guidelines
Certified CCIEs may only use the CCIE logo as provided and in accordance with the published Logo Guidelines.
Recertification
To maintain active CCIE status, CCIEs are required to pass either a CCIE written exam of their choosing from among all of the currently available written exams, or a CCIE lab exam in a new track every 24 months. Candidates can only apply one passed written exam towards recertification for every 24 month recertification period. Certification candidates are responsible for keeping track of their certification expiration dates; your recertification deadline can be viewed online anytime (with login) at Certification Status. Subsequent recertification deadlines are always based on your original certification date, not on when you took your last recertification exam.
If your CCIE recertification requirements are not completed on or before the certification's expiration date, your CCIE certification will be suspended for one year. Candidates have one year to recertify their CCIE certification by passing the required written exam. If a candidate does not recertify prior to the one year suspension period, all CCIE certification requirements must be completed again to obtain the certification (pass both the written exam and the lab exam.) Please see Recertification for detailed information.
Travel Costs
Under no circumstances will Cisco reimburse travel costs for CCIE lab exams.
Written Exam: Expiration
Candidates must make an initial attempt of the CCIE lab exam within 18 months of passing the CCIE written exam. Candidates who do not pass must re-attempt the lab exam within 12 months of their last scored attempt in order for their written exam to remain valid. If a candidate does not pass the lab exam within three years of passing the written exam, he or she must retake the written exam before being allowed to attempt the lab exam again.
Written Exam: Retakes
There is no limit to the number of attempts that can be made on the written exam. However, candidates must wait 5 calendar days between exam attempts. Once a candidate passes a particular written exam, he or she may not retake that same exam for at least 180 days. (Though rare, this may occur in certain recertification situations.)
Written Exam: Scoring
Pass marks are set by using statistical analysis and are subject to change. The pass score is given on the Examination Score Sheet at the end of the test. Along with the candidate's score, there is a notation of either PASS or FAIL. Scores on written exams are automatically downloaded from testing vendors, but may take up to 10 days to appear in the CCIE database.
PROVIDED BY CISCO SYSTEMS
Tuesday, June 29, 2010
core knowledge exam removed from ccie track
Core Knowledge Questions Removed for CCIE R&S and Voice Lab Exams
With more than six months of exam results now available, Cisco is now able to report that the troubleshooting components of the CCIE R&S v4.0 and CCIE Voice v3.0 lab exams are performing well in validating expert level networking skills. Considering these results, Cisco has decided to eliminate the Core Knowledge questions from the current CCIE R&S v4.0 and CCIE Voice v3.0 Lab Exams. Beginning on May 10, 2010, CCIE R&S and CCIE Voice Lab Exams, in all global locations, will no longer include the four open-ended Core Knowledge questions. The total lab time will remain eight hours. For the CCIE R&S Lab Exam, this means candidates will begin with the two-hour Troubleshooting section, followed by a six-hour Configuration section. For CCIE Voice, candidates will have the full eight hours to complete the integrated exam. At this time, only the R&S and Voice certifications have been designed and validated to allow removal of Core Knowledge.
With more than six months of exam results now available, Cisco is now able to report that the troubleshooting components of the CCIE R&S v4.0 and CCIE Voice v3.0 lab exams are performing well in validating expert level networking skills. Considering these results, Cisco has decided to eliminate the Core Knowledge questions from the current CCIE R&S v4.0 and CCIE Voice v3.0 Lab Exams. Beginning on May 10, 2010, CCIE R&S and CCIE Voice Lab Exams, in all global locations, will no longer include the four open-ended Core Knowledge questions. The total lab time will remain eight hours. For the CCIE R&S Lab Exam, this means candidates will begin with the two-hour Troubleshooting section, followed by a six-hour Configuration section. For CCIE Voice, candidates will have the full eight hours to complete the integrated exam. At this time, only the R&S and Voice certifications have been designed and validated to allow removal of Core Knowledge.
Thursday, June 17, 2010
HSRP vs VRRP vs GLBP
Cisco Hot-Standby Router Protocol (HSRP):
Created by Cisco, for Cisco in 1994
Uses a default hello timer of 3 seconds with a hold timer of 10 seconds
u need unique IP add. as a virtual gateway ip.
active router
standby router
Virtual Router Redundancy Protocol (VRRP)
Created by the IETF in 1999
Works between multiple vendors
Has faster timers than HSRP by default - hello of 1 second, hold timer of 3 seconds
u haven't any need of unique IP add u can use any assigned physical ip as a virtual gateway.
master router
backup router
Gateway Load Balancing Protocol (GLBP)
Created by Cisco, for Cisco in 2005
Identical features to HSRP, but allows an active-active connection that adds load-balancing features
One AVG(active virtual gateway)
Many AVF(active virtual forwarders)
Created by Cisco, for Cisco in 1994
Uses a default hello timer of 3 seconds with a hold timer of 10 seconds
u need unique IP add. as a virtual gateway ip.
active router
standby router
Virtual Router Redundancy Protocol (VRRP)
Created by the IETF in 1999
Works between multiple vendors
Has faster timers than HSRP by default - hello of 1 second, hold timer of 3 seconds
u haven't any need of unique IP add u can use any assigned physical ip as a virtual gateway.
master router
backup router
Gateway Load Balancing Protocol (GLBP)
Created by Cisco, for Cisco in 2005
Identical features to HSRP, but allows an active-active connection that adds load-balancing features
One AVG(active virtual gateway)
Many AVF(active virtual forwarders)
Monday, June 14, 2010
HSRP
HSRP stands for Hot Standy Routing Protocol which provides Automatic Router backup when an active router in the group fails. HSRP allows building resiliency in the networkgateways wherein should an Active Router fail in a HSRP group, the standby router assumes the role of the active router and continue routing packets.
HSRP works by sending multicast "Hello" messages (default: every 3 secs). If the Standby router do not receive any Hello packets from the active router for a preset time (default 10secs) then it assumes the active router is down and becomes the active router. Also, if we are tracking an interface and if the tracked interface is down, the Active Router reduces its priority so a Standby Router can assume to role of Primary Router.
A realtime example would be access to a service providers servers at a remote location. Lets say there are two distinct routes to the same server(s), each through individual routers. The clients on the internal network segment are configured to send the traffic through a gateway. The gateway being the HSRP Address. Then the Server is accessible through one service provider always (based on the active router). However, in a disaster situation when the active router goes down, the standby router assumes the active router role and continues to serve connection to the remote servers but using the other serviceprovider. This way routing redundancy is provided to a remote resource.
To setup HSRP on a pair of routers,
Router 1:
From the Interface Configuration Mode add the IP Address of the Interface
hsrp-router1#conf t
hsrp-router1(config)# int fa0/0
hsrp-router1(config-if)# ip address 192.168.0.2 255.255.255.0
Set the Virtual IP Address
Sets the Virtual IP Address for the interface where "1" is the HSRP group and "92.168.0.1" is the Virtual IP for the HSRP group.
hsrp-router1(config-if)# standby 1 ip 192.168.0.1
Enable Preempt
This is required to make the router from being a Standby Router to an Active Router when it finds the Active Router is down or if it has become the higher priority router in the group
hsrp-router1(config-if)# standby 1 preempt
Set Router Priority
The default priority is "100". We set here as "110" to make the Router 1 as active.
hsrp-router1(config-if)# standby 1 priority 110
Set Authentication String
This is an optional plain text 8 character string that can be used in the multicast "hello" packets to authenticate the HSRP group.
hsrp-router1(config-if)# standby 1 authentication LocalLAN
Set Timers
Sets the time period between the "hello" packets and the hold time before assuming an active router is down. Default is 3seconds and 10 seconds respectively.
hsrp-router1(config-if)# standby 1 timers 5 15
Track Interface
If you track interface to check link status then the following command will track an interface and when the tracked link is down, the active router will mark its priority low so as to allow a Standby router to take over.
hsrp-router1(config-if)# standby 1 track se0/0
Repeat the procedure altering the IP Address of the Local interface and the priority and the tracked interface.
Router 2:
hsrp-router2#conf t
hsrp-router2(config)# int fa0/0
hsrp-router2(config-if)# ip address 192.168.0.3 255.255.255.0
hsrp-router2(config-if)# standby 1 ip 192.168.0.1
hsrp-router2(config-if)# standby 1 preempt
hsrp-router2(config-if)# standby 1 priority 100
hsrp-router2(config-if)# standby 1 authentication LocalLAN
hsrp-router2(config-if)# standby 1 timers 5 15
hsrp-router2(config-if)# standby 1 track se0/0
Thats it. HSRP configuration is complete. You may test the connectivity to a remote route and see for yourself the redudancy in place.
HSRP works by sending multicast "Hello" messages (default: every 3 secs). If the Standby router do not receive any Hello packets from the active router for a preset time (default 10secs) then it assumes the active router is down and becomes the active router. Also, if we are tracking an interface and if the tracked interface is down, the Active Router reduces its priority so a Standby Router can assume to role of Primary Router.
A realtime example would be access to a service providers servers at a remote location. Lets say there are two distinct routes to the same server(s), each through individual routers. The clients on the internal network segment are configured to send the traffic through a gateway. The gateway being the HSRP Address. Then the Server is accessible through one service provider always (based on the active router). However, in a disaster situation when the active router goes down, the standby router assumes the active router role and continues to serve connection to the remote servers but using the other serviceprovider. This way routing redundancy is provided to a remote resource.
To setup HSRP on a pair of routers,
Router 1:
From the Interface Configuration Mode add the IP Address of the Interface
hsrp-router1#conf t
hsrp-router1(config)# int fa0/0
hsrp-router1(config-if)# ip address 192.168.0.2 255.255.255.0
Set the Virtual IP Address
Sets the Virtual IP Address for the interface where "1" is the HSRP group and "92.168.0.1" is the Virtual IP for the HSRP group.
hsrp-router1(config-if)# standby 1 ip 192.168.0.1
Enable Preempt
This is required to make the router from being a Standby Router to an Active Router when it finds the Active Router is down or if it has become the higher priority router in the group
hsrp-router1(config-if)# standby 1 preempt
Set Router Priority
The default priority is "100". We set here as "110" to make the Router 1 as active.
hsrp-router1(config-if)# standby 1 priority 110
Set Authentication String
This is an optional plain text 8 character string that can be used in the multicast "hello" packets to authenticate the HSRP group.
hsrp-router1(config-if)# standby 1 authentication LocalLAN
Set Timers
Sets the time period between the "hello" packets and the hold time before assuming an active router is down. Default is 3seconds and 10 seconds respectively.
hsrp-router1(config-if)# standby 1 timers 5 15
Track Interface
If you track interface to check link status then the following command will track an interface and when the tracked link is down, the active router will mark its priority low so as to allow a Standby router to take over.
hsrp-router1(config-if)# standby 1 track se0/0
Repeat the procedure altering the IP Address of the Local interface and the priority and the tracked interface.
Router 2:
hsrp-router2#conf t
hsrp-router2(config)# int fa0/0
hsrp-router2(config-if)# ip address 192.168.0.3 255.255.255.0
hsrp-router2(config-if)# standby 1 ip 192.168.0.1
hsrp-router2(config-if)# standby 1 preempt
hsrp-router2(config-if)# standby 1 priority 100
hsrp-router2(config-if)# standby 1 authentication LocalLAN
hsrp-router2(config-if)# standby 1 timers 5 15
hsrp-router2(config-if)# standby 1 track se0/0
Thats it. HSRP configuration is complete. You may test the connectivity to a remote route and see for yourself the redudancy in place.
Cisco EtherChannel Topologies(5)
Cisco EtherChannel Technology over CWDM
This figure shows a sample network where Gigabit links are used with Gigabit EtherChannel and CWDM technologies. In Figure 5, four gigabit links have been combined to obtain a total aggregated bandwidth of 4 gigabits. Without incorporating CWDM technologies into the solution, four runs of fiber need to be installed between the two campus points of presence (POPs). By employing CWDM GBICs and two CWDM add/drop multiplexers, the number of runs of fiber can be reduced to one. This translates into significant savings depending on the distance to be spanned by the EtherChannel connection.
Cisco EtherChannel Topologies(4)
Cisco EtherChannel Technology Interconnecting Servers, Switches, and Routers Across the Campus
This figure shows a complete network design based on Cisco EtherChannel technology. As in the previous examples, links from the wiring closets are brought into the data center using 400 Mbps channels, providing bandwidth and resiliency. In the data center, routers are interconnected with EtherChannel connections, providing improved performance by having more bandwidth available to route between subnets. Here the router is configured with two dual-link EtherChannel connections to provide 400 Mbps of bandwidth on each subnet. The EtherChannel technology provides load balancing across two links within the channel based on IP addresses, and the links within the channel can use ISL encapsulation to support multiple subnets per link. The last component in this network design is a server attached via a four-link EtherChannel connection, which provides 800 Mbps of bandwidth to the network. Typical platforms that would require such bandwidth would be high-end Pentium Pro servers, enterprise servers, and high-end graphics imaging and rendering servers. As shown in Figure 4, the server is connected via a multiple-link EtherChannel connection—an excellent match for the bandwidth needs of locally attached users and the users serviced via the router.
Cisco EtherChannel Topologies(3)
Resilience with Cisco EtherChannel Technology Using Spanning-Tree Protocol
This figure shows a configuration where a switch has been configured with two Cisco EtherChannel connections consisting of two links each. Because these are separate channels, Spanning-Tree Protocol will block the second channel to avoid the looped topology. This design is applicable where EtherChannel connections are resident on separate line cards within the switch for resiliency
EtherChannel Topologies(2)
Scaling Bandwidth with Resilience
This figure shows a topology where the network manager has increased bandwidth between the data center and the wiring closet to an aggregate of 800 Mbps, but has also used the physical diversity of the fiber plant to decrease the chances of a network outage. Using a Cisco EtherChannel connection consisting of four Fast Ethernet links, two fiber runs on the east side of the building provide 400 Mbps, and the west side of the building provides the remaining 400 Mbps. In this example, in the event of a fiber cut on one side of the building, the remaining side will pick up the traffic in less than one second, without wiring closet clients losing sessions.
Cisco EtherChannel Topologies(1)
The following diagrams show some common applications of Cisco EtherChannel technology and how they solve the bandwidth requirements of today's networks. Fast EtherChannel and Fast Ethernet links will be used throughout these examples.
This figure shows a network using Cisco EtherChannel connections. The bandwidth between the wiring closets and the data center has been doubled, from 200 Mbps to 400 Mbps. In addition to the increased bandwidth, the resiliency within the channel provides for subsecond convergence if one of the links fails.
EtherChannel (The Indians are everywhere)
EtherChannel technology was invented by Kalpana in the early 1990s. They were later acquired by Cisco Systems in 1994. In 2000 the IEEE passed 802.3ad which is an open standard version of EtherChannel.
Kalpana was a computer networking equipment manufacturer, located in Silicon Valley during the 1980s and 1990s. [1] Kalpana introduced the concept of a multi-port network switch in 1989. They also invented EtherChannel, a technology which provides additional inter-switch bandwidth by running several links in parallel. Kalpana was acquired by Cisco Systems in the year 1994 .
Kalpana had been founded by an entrepreneur of Indian origin Vinod Bhardwaj."Kalpana" meaning "imagination" in Sanskrit/Hindi was named after Vinod Bhardwaj's wife.
"By 1994, Kalpana was in a dogfight with 3Com and other switching vendors, which had embraced higher-speed uplinks and had deeper pockets for development than Kalpana had. It became clear that if Cisco were truly going to own enterprise networking, the company would have to embrace switching--and quickly."
EtherChannel is a port trunking (link aggregation being the general term) technology used primarily on Cisco switches. It allows grouping several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers. An EtherChannel can be created from between two and eight active Fast Ethernet, Gigabit Ethernet or 10-Gigabit Ethernet ports, with an additional one to eight inactive (failover) ports which become active as the other active ports fail. EtherChannel is primarily used in the backbone network, but can also be used to connect end user machines.
EtherChannel between a switch and a server.
A limitation of EtherChannel is that all the physical ports in the aggregation group must reside on the same switch, although exceptions do exist on stackable switches such as Cisco's 3750 series. Nortel's SMLT protocol removes this limitation by allowing the physical ports to be split between two switches. Cisco's Virtual Switching System allows the creation of a Multichassis Etherchannel (MEC) allowing ports to be aggregated towards different physical chassis that conform a single "virtual switch" entity.
Cisco EtherChannel Technology
Introduction
The increasing deployment of switched Ethernet to the desktop can be attributed to the proliferation of bandwidth-intensive intranet applications. Any-to-any communications of new intranet applications such as video to the desktop, interactive messaging, and collaborative white-boarding are increasing the need for scalable bandwidth within the core and at the edge of campus networks. At the same time, mission-critical applications call for resilient network designs. With the wide deployment of faster switched Ethernet links in the campus, users need to either aggregate their existing resources or upgrade the speed in their uplinks and core to scale performance across the network backbone.
Cisco EtherChannel® technology builds upon standards-based 802.3 full-duplex Fast Ethernet to provide network managers with a reliable, high-speed solution for the campus network backbone. EtherChannel technology provides bandwidth scalability within the campus by providing up to 800 Mbps, 8 Gbps, or 80 Gbps of aggregate bandwidth for a Fast EtherChannel, Gigabit EtherChannel, or 10 Gigabit EtherChannel connection, respectively. Each of these connection speeds can vary in amounts equal to the speed of the links used (100 Mbps, 1 Gbps, or 10 Gbps). Even in the most bandwidth-demanding situations, EtherChannel technology helps aggregate traffic and keep oversubscription to a minimum, while providing effective link-resiliency mechanisms.
Cisco EtherChannel Benefits
Cisco EtherChannel technology provides a solution for network managers who require higher bandwidth between servers, routers, and switches than single-link Ethernet technology can provide.
Cisco EtherChannel technology provides incremental scalable bandwidth and the following benefits:
• Standards-based—Cisco EtherChannel technology builds upon IEEE 802.3-compliant Ethernet by grouping multiple, full-duplex point-to-point links together. EtherChannel technology uses IEEE 802.3 mechanisms for full-duplex autonegotiation and autosensing, when applicable.
• Multiple platforms—Cisco EtherChannel technology is flexible and can be used anywhere in the network that bottlenecks are likely to occur. It can be used in network designs to increase bandwidth between switches and between routers and switches—as well as providing scalable bandwidth for network servers, such as large UNIX servers or PC-based Web servers.
• Flexible incremental bandwidth—Cisco EtherChannel technology provides bandwidth aggregation in multiples of 100 Mbps, 1 Gbps, or 10 Gbps, depending on the speed of the aggregated links. For example, network managers can deploy EtherChannel technology that consists of pairs of full-duplex Fast Ethernet links to provide more than 400 Mbps between the wiring closet and the data center. In the data center, bandwidths of up to 800 Mbps can be provided between servers and the network backbone to provide large amounts of scalable incremental bandwidth.
• Load balancing—Cisco EtherChannel technology is composed of several Fast Ethernet links and is capable of load balancing traffic across those links. Unicast, broadcast, and multicast traffic is evenly distributed across the links, providing higher performance and redundant parallel paths. When a link fails, traffic is redirected to the remaining links within the channel without user intervention and with minimal packet loss.
• Resiliency and fast convergence—When a link fails, Cisco EtherChannel technology provides automatic recovery by redistributing the load across the remaining links. When a link fails, Cisco EtherChannel technology redirects traffic from the failed link to the remaining links in less than one second. This convergence is transparent to the end user—no host protocol timers expire, so no sessions are dropped.
• Ease of management—Cisco EtherChannel technology takes advantage of Cisco experience developed over the years in troubleshooting and maintaining Ethernet networks. Existing network probes can be used for traffic management and troubleshooting, and management applications such as CiscoWorks and third-party management applications are now EtherChannel-aware.
• Transparent to network applications—Cisco EtherChannel technology does not require changes to networked applications. When EtherChannel technology is used within the campus, switches and routers provide load balancing across multiple links transparently to network users. To support EtherChannel technology on enterprise-class servers and network interface cards, smart software drivers can coordinate distribution of loads across multiple network interfaces.
• Compatible with Cisco IOS® Software—Cisco EtherChannel connections are fully compatible with Cisco IOS virtual LAN (VLAN) and routing technologies. The Inter-Switch Link (ISL) VLAN Trunking Protocol (VTP) can carry multiple VLANs across an EtherChannel link, and routers attached to EtherChannel trunks can provide full multiprotocol routing with support for hot standby using the Hot Standby Router Protocol (HSRP).
• 100 Megabit, 1 Gigabit, and 10 Gigabit Ethernet-ready—Cisco EtherChannel technology is available in all Ethernet link speeds. EtherChannel technology allows network managers to deploy networks that will scale smoothly with the availability of next-generation, standards-based Ethernet link speeds.
• Interoperability with Coarse Wavelength Division Multiplexing (CWDM) Gigabit Interface Converters (GBICs)—By simultaneously implementing Gigabit EtherChannel and CWDM technologies, network managers can increase the bandwidth of their links without having to invest in new long runs of fiber. CWDM technologies allow the traffic aggregated by the Cisco EtherChannel link to be multiplexed on to a single strand of fiber.
Cisco EtherChannel Components
Cisco EtherChannel technology is a trunking technology based on grouping several full-duplex 802.3 Ethernet links to provide fault-tolerant, high-speed links between switches, routers, and servers. It is based on proven industry-standard technology—it has been extended from the EtherChannel technology offered by Kalpana in its switches in the early 1990s, and provides load sharing across multiple Fast Ethernet links while providing redundancy and subsecond convergence times.
Cisco EtherChannel technology consists of the following key elements:
• Fast Ethernet links—Cisco EtherChannel connections can consist of one to eight industry-standard Fast Ethernet links to load share traffic with up to 80 Gbps of usable bandwidth. EtherChannel connections can interconnect LAN switches, routers, servers, and clients. Because load balancing is integrated with Cisco Catalyst®LAN switch architectures, there is no performance degradation for adding links to a channel—high throughput and low latencies can be maintained while gaining more available bandwidth. EtherChannel technology provides link resiliency within a channel—if links fail, the traffic is immediately directed to the remaining links. Finally, EtherChannel technology is not dependent on any type of media—it can be used with Ethernet running on existing unshielded twisted pair (UTP) wiring, or single-mode and multimode fiber.
• Cisco EtherChannel technology is a standard feature across the entire Cisco Catalyst series of switches and Cisco IOS® Software-based routers. The load-sharing algorithms used vary between platforms, allowing for decisions based on source or destination Media Access Control (MAC) addresses, IP addresses, or Transmission Control Protocol/User Datagram Protocol (TCP/UDP) port numbers.
• Redundancy—Cisco EtherChannel technology does not require the use of 802.1D Spanning-Tree Protocol to maintain a topology state within the channel. Rather, it uses a peer-to-peer control protocol that provides autoconfiguration and subsecond convergence times for parallel links, yet allows higher-level protocols (such as Spanning-Tree Protocol) or existing routing protocols to maintain topology. This approach allows EtherChannel technology to use the recovery features of the network without adding complexity or creating incompatibilities with third-party equipment or software. Because the Spanning-Tree Protocol operation is completely standards-based, network managers can use their existing network topologies, augmenting bandwidth by installing EtherChannel technology where single Ethernet links were previously installed.
• Management—Cisco EtherChannel technology is easily configured by a command-line interface (CLI) or by Simple Network Management Protocol (SNMP) applications such as CiscoWorks. A network manager needs to identify and define the number of ports that will make up the channel, and then connect the devices. CiscoWorks for Switched Internetworks will graphically display EtherChannel connections between devices, collect statistics for both individual Ethernet links within the channel, and aggregate statistics for the EtherChannel connection. An integral benefit of EtherChannel technology is the ability to detect, report, and prevent the use of incorrectly paired interfaces within the channel. These may include interfaces that are not configured for full-duplex operation, have mismatched link speeds, or are incorrectly wired. Consistency checks are completed before the activation of a channel to help ensure network integrity.
Kalpana was a computer networking equipment manufacturer, located in Silicon Valley during the 1980s and 1990s. [1] Kalpana introduced the concept of a multi-port network switch in 1989. They also invented EtherChannel, a technology which provides additional inter-switch bandwidth by running several links in parallel. Kalpana was acquired by Cisco Systems in the year 1994 .
Kalpana had been founded by an entrepreneur of Indian origin Vinod Bhardwaj."Kalpana" meaning "imagination" in Sanskrit/Hindi was named after Vinod Bhardwaj's wife.
"By 1994, Kalpana was in a dogfight with 3Com and other switching vendors, which had embraced higher-speed uplinks and had deeper pockets for development than Kalpana had. It became clear that if Cisco were truly going to own enterprise networking, the company would have to embrace switching--and quickly."
EtherChannel is a port trunking (link aggregation being the general term) technology used primarily on Cisco switches. It allows grouping several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers. An EtherChannel can be created from between two and eight active Fast Ethernet, Gigabit Ethernet or 10-Gigabit Ethernet ports, with an additional one to eight inactive (failover) ports which become active as the other active ports fail. EtherChannel is primarily used in the backbone network, but can also be used to connect end user machines.
EtherChannel between a switch and a server.
A limitation of EtherChannel is that all the physical ports in the aggregation group must reside on the same switch, although exceptions do exist on stackable switches such as Cisco's 3750 series. Nortel's SMLT protocol removes this limitation by allowing the physical ports to be split between two switches. Cisco's Virtual Switching System allows the creation of a Multichassis Etherchannel (MEC) allowing ports to be aggregated towards different physical chassis that conform a single "virtual switch" entity.
Cisco EtherChannel Technology
Introduction
The increasing deployment of switched Ethernet to the desktop can be attributed to the proliferation of bandwidth-intensive intranet applications. Any-to-any communications of new intranet applications such as video to the desktop, interactive messaging, and collaborative white-boarding are increasing the need for scalable bandwidth within the core and at the edge of campus networks. At the same time, mission-critical applications call for resilient network designs. With the wide deployment of faster switched Ethernet links in the campus, users need to either aggregate their existing resources or upgrade the speed in their uplinks and core to scale performance across the network backbone.
Cisco EtherChannel® technology builds upon standards-based 802.3 full-duplex Fast Ethernet to provide network managers with a reliable, high-speed solution for the campus network backbone. EtherChannel technology provides bandwidth scalability within the campus by providing up to 800 Mbps, 8 Gbps, or 80 Gbps of aggregate bandwidth for a Fast EtherChannel, Gigabit EtherChannel, or 10 Gigabit EtherChannel connection, respectively. Each of these connection speeds can vary in amounts equal to the speed of the links used (100 Mbps, 1 Gbps, or 10 Gbps). Even in the most bandwidth-demanding situations, EtherChannel technology helps aggregate traffic and keep oversubscription to a minimum, while providing effective link-resiliency mechanisms.
Cisco EtherChannel Benefits
Cisco EtherChannel technology provides a solution for network managers who require higher bandwidth between servers, routers, and switches than single-link Ethernet technology can provide.
Cisco EtherChannel technology provides incremental scalable bandwidth and the following benefits:
• Standards-based—Cisco EtherChannel technology builds upon IEEE 802.3-compliant Ethernet by grouping multiple, full-duplex point-to-point links together. EtherChannel technology uses IEEE 802.3 mechanisms for full-duplex autonegotiation and autosensing, when applicable.
• Multiple platforms—Cisco EtherChannel technology is flexible and can be used anywhere in the network that bottlenecks are likely to occur. It can be used in network designs to increase bandwidth between switches and between routers and switches—as well as providing scalable bandwidth for network servers, such as large UNIX servers or PC-based Web servers.
• Flexible incremental bandwidth—Cisco EtherChannel technology provides bandwidth aggregation in multiples of 100 Mbps, 1 Gbps, or 10 Gbps, depending on the speed of the aggregated links. For example, network managers can deploy EtherChannel technology that consists of pairs of full-duplex Fast Ethernet links to provide more than 400 Mbps between the wiring closet and the data center. In the data center, bandwidths of up to 800 Mbps can be provided between servers and the network backbone to provide large amounts of scalable incremental bandwidth.
• Load balancing—Cisco EtherChannel technology is composed of several Fast Ethernet links and is capable of load balancing traffic across those links. Unicast, broadcast, and multicast traffic is evenly distributed across the links, providing higher performance and redundant parallel paths. When a link fails, traffic is redirected to the remaining links within the channel without user intervention and with minimal packet loss.
• Resiliency and fast convergence—When a link fails, Cisco EtherChannel technology provides automatic recovery by redistributing the load across the remaining links. When a link fails, Cisco EtherChannel technology redirects traffic from the failed link to the remaining links in less than one second. This convergence is transparent to the end user—no host protocol timers expire, so no sessions are dropped.
• Ease of management—Cisco EtherChannel technology takes advantage of Cisco experience developed over the years in troubleshooting and maintaining Ethernet networks. Existing network probes can be used for traffic management and troubleshooting, and management applications such as CiscoWorks and third-party management applications are now EtherChannel-aware.
• Transparent to network applications—Cisco EtherChannel technology does not require changes to networked applications. When EtherChannel technology is used within the campus, switches and routers provide load balancing across multiple links transparently to network users. To support EtherChannel technology on enterprise-class servers and network interface cards, smart software drivers can coordinate distribution of loads across multiple network interfaces.
• Compatible with Cisco IOS® Software—Cisco EtherChannel connections are fully compatible with Cisco IOS virtual LAN (VLAN) and routing technologies. The Inter-Switch Link (ISL) VLAN Trunking Protocol (VTP) can carry multiple VLANs across an EtherChannel link, and routers attached to EtherChannel trunks can provide full multiprotocol routing with support for hot standby using the Hot Standby Router Protocol (HSRP).
• 100 Megabit, 1 Gigabit, and 10 Gigabit Ethernet-ready—Cisco EtherChannel technology is available in all Ethernet link speeds. EtherChannel technology allows network managers to deploy networks that will scale smoothly with the availability of next-generation, standards-based Ethernet link speeds.
• Interoperability with Coarse Wavelength Division Multiplexing (CWDM) Gigabit Interface Converters (GBICs)—By simultaneously implementing Gigabit EtherChannel and CWDM technologies, network managers can increase the bandwidth of their links without having to invest in new long runs of fiber. CWDM technologies allow the traffic aggregated by the Cisco EtherChannel link to be multiplexed on to a single strand of fiber.
Cisco EtherChannel Components
Cisco EtherChannel technology is a trunking technology based on grouping several full-duplex 802.3 Ethernet links to provide fault-tolerant, high-speed links between switches, routers, and servers. It is based on proven industry-standard technology—it has been extended from the EtherChannel technology offered by Kalpana in its switches in the early 1990s, and provides load sharing across multiple Fast Ethernet links while providing redundancy and subsecond convergence times.
Cisco EtherChannel technology consists of the following key elements:
• Fast Ethernet links—Cisco EtherChannel connections can consist of one to eight industry-standard Fast Ethernet links to load share traffic with up to 80 Gbps of usable bandwidth. EtherChannel connections can interconnect LAN switches, routers, servers, and clients. Because load balancing is integrated with Cisco Catalyst®LAN switch architectures, there is no performance degradation for adding links to a channel—high throughput and low latencies can be maintained while gaining more available bandwidth. EtherChannel technology provides link resiliency within a channel—if links fail, the traffic is immediately directed to the remaining links. Finally, EtherChannel technology is not dependent on any type of media—it can be used with Ethernet running on existing unshielded twisted pair (UTP) wiring, or single-mode and multimode fiber.
• Cisco EtherChannel technology is a standard feature across the entire Cisco Catalyst series of switches and Cisco IOS® Software-based routers. The load-sharing algorithms used vary between platforms, allowing for decisions based on source or destination Media Access Control (MAC) addresses, IP addresses, or Transmission Control Protocol/User Datagram Protocol (TCP/UDP) port numbers.
• Redundancy—Cisco EtherChannel technology does not require the use of 802.1D Spanning-Tree Protocol to maintain a topology state within the channel. Rather, it uses a peer-to-peer control protocol that provides autoconfiguration and subsecond convergence times for parallel links, yet allows higher-level protocols (such as Spanning-Tree Protocol) or existing routing protocols to maintain topology. This approach allows EtherChannel technology to use the recovery features of the network without adding complexity or creating incompatibilities with third-party equipment or software. Because the Spanning-Tree Protocol operation is completely standards-based, network managers can use their existing network topologies, augmenting bandwidth by installing EtherChannel technology where single Ethernet links were previously installed.
• Management—Cisco EtherChannel technology is easily configured by a command-line interface (CLI) or by Simple Network Management Protocol (SNMP) applications such as CiscoWorks. A network manager needs to identify and define the number of ports that will make up the channel, and then connect the devices. CiscoWorks for Switched Internetworks will graphically display EtherChannel connections between devices, collect statistics for both individual Ethernet links within the channel, and aggregate statistics for the EtherChannel connection. An integral benefit of EtherChannel technology is the ability to detect, report, and prevent the use of incorrectly paired interfaces within the channel. These may include interfaces that are not configured for full-duplex operation, have mismatched link speeds, or are incorrectly wired. Consistency checks are completed before the activation of a channel to help ensure network integrity.
Saturday, June 12, 2010
EtherChannel on various models of Cisco Switches
Catalyst 4500/4000 Series
Catalyst OS
In the Catalyst 4500/4000 series switches with CatOS (Supervisor Engine I and II), you can form an EtherChannel with up to eight compatibly configured Fast Ethernet or Gigabit Ethernet ports on the switch. The exact EtherChannel formation depends on the hardware. Because the spanning tree feature handles the port ID, the maximum number of channels is 126 for a six-slot chassis. In addition, you can configure an EtherChannel with the use of ports from multiple modules in CatOS release 5.x and later. All ports in an EtherChannel must be the same speed.
Catalyst OS for Catalyst 4500/4000 uses MAC address based load balancing. EtherChannel distributes frames across the links in a channel based on the low-order bits of the source and destination MAC addresses of each frame. The frame distribution method is not configurable.
Cisco IOS
A Catalyst 4500/4000 series switch with Cisco IOS Software (Supervisor Engine II+ and later) supports a maximum of 64 EtherChannels. You can form an EtherChannel with up to eight compatibly configured Ethernet interfaces on any module and across modules. All interfaces in each EtherChannel must be the same speed, and you must configure all the interfaces as either Layer 2 or Layer 3 interfaces.
EtherChannel reduces part of the binary pattern that is formed from the addresses in the frame to a numerical value that selects one of the links in the channel in order to balance the traffic load across the links in a channel. EtherChannel load balancing can use MAC addresses, IP addresses, or Layer 4 port numbers and either source mode, destination mode, or both. Use the option that provides the greatest variety in your configuration. For example, if the traffic on a channel only goes to a single MAC address, use of the destination MAC address results in the choice of the same link in the channel each time. Use of source or IP addresses can result in a better load balance. Issue the port-channel load-balance {src-mac | dst-mac | src-dst-mac | src-ip | dst-ip | src-dst-ip | src-port | dst-port | src-dst-port} global configuration command in order to configure load balancing. Load Balance must be configured globally and the load balancing option cannot be changed on a per port basis.
Note: The switch uses the lower order bits of source MAC address and destination MAC address in order to determine which links must be used to transmit the data. So if the data is received from the same source, then same link of the EtherChannel is used in order to forward the data.
Catalyst 2900XL/3500XL Series
A Catalyst 2900XL that runs a Cisco IOS software release that is earlier than Cisco IOS Software Release 11.2(8)SA3 chooses a link in the channel based on the link on which the destination MAC address was last heard. The software dynamically reallocates this address to another link in the channel if the link on which the address was learned is busier than the others. You can configure a Catalyst 2900XL that runs Cisco IOS Software Release 11.2(8)SA3 or later and a Catalyst 3500XL that runs Cisco IOS Software Release 11.2(8)SA6 or later in order to choose a link to be sent across the Fast EtherChannel. The switch chooses the link on the basis of the destination or source MAC address of the frame. The default is to use the source MAC address. This default means that all packets that the switch receives on a non-Fast EtherChannel port with the same MAC source address that have a destination of the MAC addresses on the other side of the channel take the same link in the channel. Use source-based forwarding when many stations that are attached to the Catalyst 2900XL/3500XL send to a few stations, such as a single router, on the other side of the Fast EtherChannel. The use of source-based forwarding in this situation evenly distributes traffic across all links in the channel. Also, the Catalyst 2900XL/3500XL switches maintain a notion of a default port on which to transmit traffic, such as Spanning Tree Protocol (STP), multicasts, and unknown unicasts.
Catalyst 3750/3560
The Catalyst 3750/3560 series switch can support up to eight compatibly configured Ethernet interfaces in an EtherChannel. The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 8 Gbps (Gigabit EtherChannel) between your switch and another switch or host. With Cisco IOS Software Release 12.2(20)SE and earlier, the number of EtherChannels has a limit of 12. With Cisco IOS Software Release 12.2(25)SE and later, the number of EtherChannels has a limit of 48.
EtherChannel balances the traffic load across the links in a channel through the reduction of part of the binary pattern that the addresses in the frame form to a numerical value that selects one of the links in the channel. EtherChannel load balancing can use MAC addresses or IP addresses, source or destination addresses, or both source and destination addresses. The mode applies to all EtherChannels that are configured on the switch. You configure the load balancing and forwarding method with use of the port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac} global configuration command.
You can find out which interface is used in the EtherChannel to forward traffic based on the load balancing method. The command for this determination is test etherchannel load-balance interface port-channel number {ip | mac} [source_ip_add | source_mac_add] [dest_ip_add | dest_mac_add].
Catalyst 2950/2955/3550
The Catalyst 2950/2955 series switch can support up to eight compatibly configured Ethernet interfaces in an EtherChannel. The EtherChannel can provide full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 2 Gbps (Gigabit EtherChannel) between your switch and another switch or host. The number of EtherChannels has the limit of six with eight ports per EtherChannel.
The Catalyst 3550 series switches support both Layer 2 and Layer 3 EtherChannel, with up to eight compatibly configured Ethernet interfaces. The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 8 Gbps (Gigabit EtherChannel) between your switch and another switch or host. The limit of the number of EtherChannels is the number of ports of the same type.
For the 2950/2955/3550 series switch, EtherChannel balances the traffic load across the links in a channel by randomly associating a newly learned MAC address with one of the links in the channel. EtherChannel load balancing can use either source-MAC or destination-MAC address forwarding.
With source-MAC address forwarding, when packets are forwarded to an EtherChannel, the packets are distributed across the ports in the channel based on the source-MAC address of the incoming packet. Therefore, to provide load balancing, packets from different hosts use different ports in the channel, but packets from the same host use the same port in the channel. With destination-MAC address forwarding, when packets are forwarded to an EtherChannel, the packets are distributed across the ports in the channel based on the destination host MAC address of the incoming packet. Therefore, packets to the same destination are forwarded over the same port, and packets to a different destination are sent on a different port in the channel.
For the 3550 series switch, when source-MAC address forwarding is used, load distribution based on the source and destination IP address is also enabled for routed IP traffic. All routed IP traffic chooses a port based on the source and destination IP address. Packets between two IP hosts always use the same port in the channel, and traffic between any other pair of hosts can use a different port in the channel.
Issue the port-channel load-balance {dst-mac | src-mac} global configuration command in order to configure the load-balance and forward method.
Note: The default port is used to transmit traffic, such as Spanning Tree Protocol (STP), multicasts, and unknown unicasts. The default port can be identified from the output of the command show etherchannel summary by a notation of d.
Catalyst 1900/2820
With the enablement of PAgP, the two possible methods of link determination are preserve order and maximize load balancing between the links on the Fast EtherChannel. The What Is PAgP and Where Do You Use It? section of this document describes PAgP. The default is to maximize load balancing. PAgP is used to negotiate the configured method with the device at the other side of the channel. If preserve order is configured, the device at the other side is instructed in order to use source-based transmissions so that the Catalyst 1900/2820 always receives packets with the same source MAC address on the same link in the channel. This is the link that the Catalyst 1900/2820 always uses to send traffic to this MAC address. If maximize load balancing is configured, PAgP tells the other side that it can distribute traffic arbitrarily, and unicast traffic is transmitted by the Catalyst 1900/2820 on the link where the source address was last seen. This provides the maximum possible load-balancing configuration. When Fast EtherChannel is configured with PAgP disabled, the switch cannot negotiate with the partner about the switch learning capability. Whether the switch preserves frame ordering depends on whether the Fast EtherChannel partner performs source-based distribution. The Catalyst 1900/2820s also elect an active port. The active port is used for flooded traffic such as unknown unicast, unregistered multicast, and broadcast packets. If the port-channel mode is on (PAgP disabled), the active port is the link with the highest priority value. If the mode is desirable or auto (PAgP enabled), the active port is selected based on the priority of the links on the switch that has the higher Ethernet address. When two ports on the switch with the higher Ethernet address have the same priority, the port with the lower ifIndex is selected.
Catalyst 2948G-L3/4908G-L3 and Catalyst 8500
When one link fails, all traffic that previously used that link now uses the link next to it. For example, if Link 1 fails in a bundle, traffic that previously used Link 1 before the failure now uses Link 2.
Catalyst OS
In the Catalyst 4500/4000 series switches with CatOS (Supervisor Engine I and II), you can form an EtherChannel with up to eight compatibly configured Fast Ethernet or Gigabit Ethernet ports on the switch. The exact EtherChannel formation depends on the hardware. Because the spanning tree feature handles the port ID, the maximum number of channels is 126 for a six-slot chassis. In addition, you can configure an EtherChannel with the use of ports from multiple modules in CatOS release 5.x and later. All ports in an EtherChannel must be the same speed.
Catalyst OS for Catalyst 4500/4000 uses MAC address based load balancing. EtherChannel distributes frames across the links in a channel based on the low-order bits of the source and destination MAC addresses of each frame. The frame distribution method is not configurable.
Cisco IOS
A Catalyst 4500/4000 series switch with Cisco IOS Software (Supervisor Engine II+ and later) supports a maximum of 64 EtherChannels. You can form an EtherChannel with up to eight compatibly configured Ethernet interfaces on any module and across modules. All interfaces in each EtherChannel must be the same speed, and you must configure all the interfaces as either Layer 2 or Layer 3 interfaces.
EtherChannel reduces part of the binary pattern that is formed from the addresses in the frame to a numerical value that selects one of the links in the channel in order to balance the traffic load across the links in a channel. EtherChannel load balancing can use MAC addresses, IP addresses, or Layer 4 port numbers and either source mode, destination mode, or both. Use the option that provides the greatest variety in your configuration. For example, if the traffic on a channel only goes to a single MAC address, use of the destination MAC address results in the choice of the same link in the channel each time. Use of source or IP addresses can result in a better load balance. Issue the port-channel load-balance {src-mac | dst-mac | src-dst-mac | src-ip | dst-ip | src-dst-ip | src-port | dst-port | src-dst-port} global configuration command in order to configure load balancing. Load Balance must be configured globally and the load balancing option cannot be changed on a per port basis.
Note: The switch uses the lower order bits of source MAC address and destination MAC address in order to determine which links must be used to transmit the data. So if the data is received from the same source, then same link of the EtherChannel is used in order to forward the data.
Catalyst 2900XL/3500XL Series
A Catalyst 2900XL that runs a Cisco IOS software release that is earlier than Cisco IOS Software Release 11.2(8)SA3 chooses a link in the channel based on the link on which the destination MAC address was last heard. The software dynamically reallocates this address to another link in the channel if the link on which the address was learned is busier than the others. You can configure a Catalyst 2900XL that runs Cisco IOS Software Release 11.2(8)SA3 or later and a Catalyst 3500XL that runs Cisco IOS Software Release 11.2(8)SA6 or later in order to choose a link to be sent across the Fast EtherChannel. The switch chooses the link on the basis of the destination or source MAC address of the frame. The default is to use the source MAC address. This default means that all packets that the switch receives on a non-Fast EtherChannel port with the same MAC source address that have a destination of the MAC addresses on the other side of the channel take the same link in the channel. Use source-based forwarding when many stations that are attached to the Catalyst 2900XL/3500XL send to a few stations, such as a single router, on the other side of the Fast EtherChannel. The use of source-based forwarding in this situation evenly distributes traffic across all links in the channel. Also, the Catalyst 2900XL/3500XL switches maintain a notion of a default port on which to transmit traffic, such as Spanning Tree Protocol (STP), multicasts, and unknown unicasts.
Catalyst 3750/3560
The Catalyst 3750/3560 series switch can support up to eight compatibly configured Ethernet interfaces in an EtherChannel. The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 8 Gbps (Gigabit EtherChannel) between your switch and another switch or host. With Cisco IOS Software Release 12.2(20)SE and earlier, the number of EtherChannels has a limit of 12. With Cisco IOS Software Release 12.2(25)SE and later, the number of EtherChannels has a limit of 48.
EtherChannel balances the traffic load across the links in a channel through the reduction of part of the binary pattern that the addresses in the frame form to a numerical value that selects one of the links in the channel. EtherChannel load balancing can use MAC addresses or IP addresses, source or destination addresses, or both source and destination addresses. The mode applies to all EtherChannels that are configured on the switch. You configure the load balancing and forwarding method with use of the port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac} global configuration command.
You can find out which interface is used in the EtherChannel to forward traffic based on the load balancing method. The command for this determination is test etherchannel load-balance interface port-channel number {ip | mac} [source_ip_add | source_mac_add] [dest_ip_add | dest_mac_add].
Catalyst 2950/2955/3550
The Catalyst 2950/2955 series switch can support up to eight compatibly configured Ethernet interfaces in an EtherChannel. The EtherChannel can provide full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 2 Gbps (Gigabit EtherChannel) between your switch and another switch or host. The number of EtherChannels has the limit of six with eight ports per EtherChannel.
The Catalyst 3550 series switches support both Layer 2 and Layer 3 EtherChannel, with up to eight compatibly configured Ethernet interfaces. The EtherChannel provides full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 8 Gbps (Gigabit EtherChannel) between your switch and another switch or host. The limit of the number of EtherChannels is the number of ports of the same type.
For the 2950/2955/3550 series switch, EtherChannel balances the traffic load across the links in a channel by randomly associating a newly learned MAC address with one of the links in the channel. EtherChannel load balancing can use either source-MAC or destination-MAC address forwarding.
With source-MAC address forwarding, when packets are forwarded to an EtherChannel, the packets are distributed across the ports in the channel based on the source-MAC address of the incoming packet. Therefore, to provide load balancing, packets from different hosts use different ports in the channel, but packets from the same host use the same port in the channel. With destination-MAC address forwarding, when packets are forwarded to an EtherChannel, the packets are distributed across the ports in the channel based on the destination host MAC address of the incoming packet. Therefore, packets to the same destination are forwarded over the same port, and packets to a different destination are sent on a different port in the channel.
For the 3550 series switch, when source-MAC address forwarding is used, load distribution based on the source and destination IP address is also enabled for routed IP traffic. All routed IP traffic chooses a port based on the source and destination IP address. Packets between two IP hosts always use the same port in the channel, and traffic between any other pair of hosts can use a different port in the channel.
Issue the port-channel load-balance {dst-mac | src-mac} global configuration command in order to configure the load-balance and forward method.
Note: The default port is used to transmit traffic, such as Spanning Tree Protocol (STP), multicasts, and unknown unicasts. The default port can be identified from the output of the command show etherchannel summary by a notation of d.
Catalyst 1900/2820
With the enablement of PAgP, the two possible methods of link determination are preserve order and maximize load balancing between the links on the Fast EtherChannel. The What Is PAgP and Where Do You Use It? section of this document describes PAgP. The default is to maximize load balancing. PAgP is used to negotiate the configured method with the device at the other side of the channel. If preserve order is configured, the device at the other side is instructed in order to use source-based transmissions so that the Catalyst 1900/2820 always receives packets with the same source MAC address on the same link in the channel. This is the link that the Catalyst 1900/2820 always uses to send traffic to this MAC address. If maximize load balancing is configured, PAgP tells the other side that it can distribute traffic arbitrarily, and unicast traffic is transmitted by the Catalyst 1900/2820 on the link where the source address was last seen. This provides the maximum possible load-balancing configuration. When Fast EtherChannel is configured with PAgP disabled, the switch cannot negotiate with the partner about the switch learning capability. Whether the switch preserves frame ordering depends on whether the Fast EtherChannel partner performs source-based distribution. The Catalyst 1900/2820s also elect an active port. The active port is used for flooded traffic such as unknown unicast, unregistered multicast, and broadcast packets. If the port-channel mode is on (PAgP disabled), the active port is the link with the highest priority value. If the mode is desirable or auto (PAgP enabled), the active port is selected based on the priority of the links on the switch that has the higher Ethernet address. When two ports on the switch with the higher Ethernet address have the same priority, the port with the lower ifIndex is selected.
Catalyst 2948G-L3/4908G-L3 and Catalyst 8500
When one link fails, all traffic that previously used that link now uses the link next to it. For example, if Link 1 fails in a bundle, traffic that previously used Link 1 before the failure now uses Link 2.
Thursday, June 10, 2010
Unequal load split with static routes
Unequal load-sharing with static routes is almost impossible as there is no configuration command to assign non-default traffic share count to a static route. For example, if you configure two default routes, one pointing to a low-speed interface and another one pointing to a high-speed interface, there is no mechanism to force majority of the traffic onto the high-speed link (IOS ignores interface bandwidth when calculating load sharing ratios).
You can, howerer, use a workaround: if you configure multiple routes for the same prefix pointing to the same interface, that interface will attract proportionally more outbound traffic.
For example, let's assume you have two point-to-point serial subinterfaces, one three times as fast as the other:
interface Serial0/0/0.100 point-to-point
bandwidth 1000
ip address 172.16.1.1 255.255.255.252
!
interface Serial0/0/0.200 point-to-point
ip address 172.16.1.5 255.255.255.252
bandwidth 3000
To shift more traffic onto Serial0/0/0.200, you can create two default routes pointing to the second interface, one pointing to the interface itself, the other one to the next-hop router:
ip route 0.0.0.0 0.0.0.0 Serial0/0/0.100
ip route 0.0.0.0 0.0.0.0 Serial0/0/0.200
ip route 0.0.0.0 0.0.0.0 172.16.1.6
This setup will give you a 1:2 sharing ratio. To shift even more traffic to the higher-speed interface, one has to get more creative
Create a bogus host route for a bogus next-hop pointing to the actual next-hop router (and make sure you don't advertise the bogus route into your routing protocols).
Configure yet another static route pointing to the bogus next-hop. Due to recursive lookup done by Cisco IOS, the bogus next-hop will be resolved into the actual next-hop IP address.
In our example, you could use:
ip route 10.255.255.1 255.255.255.255 172.16.1.6
ip route 0.0.0.0 0.0.0.0 10.255.255.1
The results are as expected: the traffic split is the desired 1:3 ratio
a1#show ip route 0.0.0.0 0.0.0.0
Routing entry for 0.0.0.0 0.0.0.0, supernet
Known via "static", distance 1, metric 0 (connected), candidate default path
Routing Descriptor Blocks:
172.16.1.6
Route metric is 0, traffic share count is 1
10.255.255.1
Route metric is 0, traffic share count is 1
* directly connected, via Serial0/0/0.100
Route metric is 0, traffic share count is 1
directly connected, via Serial0/0/0.200
Route metric is 0, traffic share count is 1
a1#show ip cef 0.0.0.0 0.0.0.0 internal
0.0.0.0/0, version 43, epoch 0, attached, per-destination sharing
0 packets, 0 bytes
via 172.16.1.6, 0 dependencies, recursive
traffic share 1
valid adjacency
via 10.255.255.1, 0 dependencies, recursive
traffic share 1
valid adjacency
via Serial0/0/0.100, 0 dependencies
traffic share 1
valid adjacency
via Serial0/0/0.200, 0 dependencies
traffic share 1
valid adjacency
0 packets, 0 bytes switched through the prefix
tmstats: external 0 packets, 0 bytes
internal 0 packets, 0 bytes
Load distribution: 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 (refcount 1)
Hash OK Interface Address Packets
1 Y Serial0/0/0.200 point2point 0
2 Y Serial0/0/0.200 point2point 0
3 Y Serial0/0/0.100 point2point 0
4 Y Serial0/0/0.200 point2point 0
5 Y Serial0/0/0.200 point2point 0
6 Y Serial0/0/0.200 point2point 0
7 Y Serial0/0/0.100 point2point 0
8 Y Serial0/0/0.200 point2point 0
9 Y Serial0/0/0.200 point2point 0
10 Y Serial0/0/0.200 point2point 0
11 Y Serial0/0/0.100 point2point 0
12 Y Serial0/0/0.200 point2point 0
13 Y Serial0/0/0.200 point2point 0
14 Y Serial0/0/0.200 point2point 0
15 Y Serial0/0/0.100 point2point 0
16 Y Serial0/0/0.200 point2point 0
Read more: http://blog.ioshints.info/2007/02/unequal-load-split-with-static-routes.html#ixzz0qTjNprvX
You can, howerer, use a workaround: if you configure multiple routes for the same prefix pointing to the same interface, that interface will attract proportionally more outbound traffic.
For example, let's assume you have two point-to-point serial subinterfaces, one three times as fast as the other:
interface Serial0/0/0.100 point-to-point
bandwidth 1000
ip address 172.16.1.1 255.255.255.252
!
interface Serial0/0/0.200 point-to-point
ip address 172.16.1.5 255.255.255.252
bandwidth 3000
To shift more traffic onto Serial0/0/0.200, you can create two default routes pointing to the second interface, one pointing to the interface itself, the other one to the next-hop router:
ip route 0.0.0.0 0.0.0.0 Serial0/0/0.100
ip route 0.0.0.0 0.0.0.0 Serial0/0/0.200
ip route 0.0.0.0 0.0.0.0 172.16.1.6
This setup will give you a 1:2 sharing ratio. To shift even more traffic to the higher-speed interface, one has to get more creative
Create a bogus host route for a bogus next-hop pointing to the actual next-hop router (and make sure you don't advertise the bogus route into your routing protocols).
Configure yet another static route pointing to the bogus next-hop. Due to recursive lookup done by Cisco IOS, the bogus next-hop will be resolved into the actual next-hop IP address.
In our example, you could use:
ip route 10.255.255.1 255.255.255.255 172.16.1.6
ip route 0.0.0.0 0.0.0.0 10.255.255.1
The results are as expected: the traffic split is the desired 1:3 ratio
a1#show ip route 0.0.0.0 0.0.0.0
Routing entry for 0.0.0.0 0.0.0.0, supernet
Known via "static", distance 1, metric 0 (connected), candidate default path
Routing Descriptor Blocks:
172.16.1.6
Route metric is 0, traffic share count is 1
10.255.255.1
Route metric is 0, traffic share count is 1
* directly connected, via Serial0/0/0.100
Route metric is 0, traffic share count is 1
directly connected, via Serial0/0/0.200
Route metric is 0, traffic share count is 1
a1#show ip cef 0.0.0.0 0.0.0.0 internal
0.0.0.0/0, version 43, epoch 0, attached, per-destination sharing
0 packets, 0 bytes
via 172.16.1.6, 0 dependencies, recursive
traffic share 1
valid adjacency
via 10.255.255.1, 0 dependencies, recursive
traffic share 1
valid adjacency
via Serial0/0/0.100, 0 dependencies
traffic share 1
valid adjacency
via Serial0/0/0.200, 0 dependencies
traffic share 1
valid adjacency
0 packets, 0 bytes switched through the prefix
tmstats: external 0 packets, 0 bytes
internal 0 packets, 0 bytes
Load distribution: 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 (refcount 1)
Hash OK Interface Address Packets
1 Y Serial0/0/0.200 point2point 0
2 Y Serial0/0/0.200 point2point 0
3 Y Serial0/0/0.100 point2point 0
4 Y Serial0/0/0.200 point2point 0
5 Y Serial0/0/0.200 point2point 0
6 Y Serial0/0/0.200 point2point 0
7 Y Serial0/0/0.100 point2point 0
8 Y Serial0/0/0.200 point2point 0
9 Y Serial0/0/0.200 point2point 0
10 Y Serial0/0/0.200 point2point 0
11 Y Serial0/0/0.100 point2point 0
12 Y Serial0/0/0.200 point2point 0
13 Y Serial0/0/0.200 point2point 0
14 Y Serial0/0/0.200 point2point 0
15 Y Serial0/0/0.100 point2point 0
16 Y Serial0/0/0.200 point2point 0
Read more: http://blog.ioshints.info/2007/02/unequal-load-split-with-static-routes.html#ixzz0qTjNprvX
most favorite interview questions by recruiters...(3)
Que-1 Explain TCP handshake.
Answer: syn
syn-ack
ack
Que-2 How does spanning tree prevent loops?
Answer: By selecting a root bridge ( lowest priority)
Determine the least cost paths to the root bridge on each segement - designated ports
Disable all other root paths.
Que-3 What are the 5 port states?
?Port States
Legacy ST Rapid ST
Answer: Disabled
Blocking Discarding
Listening
Learning Learning
Forwarding Forwarding
Que-4 Name most usable BGP attributes.
Answer: Weight
Local preference
Multi-exit discriminator
Origin
AS_path
Next hop
Community
Que-5 What is IGMP snooping used for?
Answer: To cut down on switch resources. It checks each multicast packet for joins/leaves
Que-6 How is a mulitcast designated router elected?
Answer: Highest IP address
Que-7 You have area 0 and area 1, what is the router in between these two area's called?
Answer: ABR
Que-8 how to create end-to-end MPLS VPNs using multiple carrier MPLS networks. LOL I nearly died.
Answer: MPLS-ICI device much like a FR NNI interface. And then import/export the route targets that correspond to the particular VPN.
Que-9 Name some issues with QoS when traversing multiple ISP networks?
Answer: One ISP might use DSCP, one might use IP Precedence and the third might use DSCP also, hence there needs to be an agreement end-to-end for proper QoS propagation
Que-10 When tracking an interface using HSRP (or another protocol) how would you know that a Metro Ethernet link is down?
Answer: In metro ethernet we usually see the link as UP/UP, even though the CE router has lost connection to the aggregation switch, because of this we cannot take the interface protocol as our main way of telling connectivity. We can use ICMP and IP SLA to track an object in this case. Or else some way check the protocol status such as BGP (as this will be in active)
Answer: syn
syn-ack
ack
Que-2 How does spanning tree prevent loops?
Answer: By selecting a root bridge ( lowest priority)
Determine the least cost paths to the root bridge on each segement - designated ports
Disable all other root paths.
Que-3 What are the 5 port states?
?Port States
Legacy ST Rapid ST
Answer: Disabled
Blocking Discarding
Listening
Learning Learning
Forwarding Forwarding
Que-4 Name most usable BGP attributes.
Answer: Weight
Local preference
Multi-exit discriminator
Origin
AS_path
Next hop
Community
Que-5 What is IGMP snooping used for?
Answer: To cut down on switch resources. It checks each multicast packet for joins/leaves
Que-6 How is a mulitcast designated router elected?
Answer: Highest IP address
Que-7 You have area 0 and area 1, what is the router in between these two area's called?
Answer: ABR
Que-8 how to create end-to-end MPLS VPNs using multiple carrier MPLS networks. LOL I nearly died.
Answer: MPLS-ICI device much like a FR NNI interface. And then import/export the route targets that correspond to the particular VPN.
Que-9 Name some issues with QoS when traversing multiple ISP networks?
Answer: One ISP might use DSCP, one might use IP Precedence and the third might use DSCP also, hence there needs to be an agreement end-to-end for proper QoS propagation
Que-10 When tracking an interface using HSRP (or another protocol) how would you know that a Metro Ethernet link is down?
Answer: In metro ethernet we usually see the link as UP/UP, even though the CE router has lost connection to the aggregation switch, because of this we cannot take the interface protocol as our main way of telling connectivity. We can use ICMP and IP SLA to track an object in this case. Or else some way check the protocol status such as BGP (as this will be in active)
most favorite interview questions by recruiters...(2)
Que-1 what is the difference between acknowledgments and handshaking?
Answer: Handshaking is used to negotiate the properties of a connection that is being established. Acknowledgments are used to tell the sender that data has been successfully received by the destination during the use of a connection.
Que-2 What do you need with BGP when you have a firewall between peers?
Answer: ebgp multihop
Que-3 If you look at the routing table what does IA mean?
Answer: inter area route
Que-4 In OSPF if you want the metric to increase on external routes what do you need to do?
Answer: metric type 1
Que-5 You have one public IP but you have many hosts what can you do?
Answer: Nat with overload (PAT)
Que-6 What are the possible reasons for stuck in active?
Answer: Link failure
Que-7 How is the root bridge elected?
Answer: lowest mac address ( bridge id)
Que-8 How do you set up dhcp on a router?
Answer: ip dhcp pool DHCPPOOL
domain-name hiremenow.com
network x.x.x.x/x
dns-server x.x.x.x x.x.x.x
default-router x.x.x.x
excludes...
Que-9 Explain how Eigrp works?
Answer: Routers send out hello's and forms neighbor relationships.
Each router receives advertisements from each neighbor with AD(metric) and FD (feasible distance) to a route. FD is the metric from this router through the neighbor to the network.
EIGRP uses the DUAL algorithm to choose best paths by looking
at AD and FD. The path with the lowest metric(AD) is called the successor
path. EIGRP paths with a lower AD than the FD of the successor path
are guaranteed loop-free and called feasible successors.
Lowest FD = successor path.
Lowest AD = feasible successor.
Que-10 How is a shortest path tree built? (Multicast)
Answer: PIM-SM uses a shared tree to distribute the information about active sources. Once the traffic knows the best path it switches over to an optimized source distribution tree.
Answer: Handshaking is used to negotiate the properties of a connection that is being established. Acknowledgments are used to tell the sender that data has been successfully received by the destination during the use of a connection.
Que-2 What do you need with BGP when you have a firewall between peers?
Answer: ebgp multihop
Que-3 If you look at the routing table what does IA mean?
Answer: inter area route
Que-4 In OSPF if you want the metric to increase on external routes what do you need to do?
Answer: metric type 1
Que-5 You have one public IP but you have many hosts what can you do?
Answer: Nat with overload (PAT)
Que-6 What are the possible reasons for stuck in active?
Answer: Link failure
Que-7 How is the root bridge elected?
Answer: lowest mac address ( bridge id)
Que-8 How do you set up dhcp on a router?
Answer: ip dhcp pool DHCPPOOL
domain-name hiremenow.com
network x.x.x.x/x
dns-server x.x.x.x x.x.x.x
default-router x.x.x.x
excludes...
Que-9 Explain how Eigrp works?
Answer: Routers send out hello's and forms neighbor relationships.
Each router receives advertisements from each neighbor with AD(metric) and FD (feasible distance) to a route. FD is the metric from this router through the neighbor to the network.
EIGRP uses the DUAL algorithm to choose best paths by looking
at AD and FD. The path with the lowest metric(AD) is called the successor
path. EIGRP paths with a lower AD than the FD of the successor path
are guaranteed loop-free and called feasible successors.
Lowest FD = successor path.
Lowest AD = feasible successor.
Que-10 How is a shortest path tree built? (Multicast)
Answer: PIM-SM uses a shared tree to distribute the information about active sources. Once the traffic knows the best path it switches over to an optimized source distribution tree.
most favorite interview questions by recruiters...(1)
Q-1 Which layer of the OSI model is responsible for reliable connections?
Answer: The Transport layer of the OSI model is responsible for reliable connections.
Q-2 What is the difference between acknowledgments and handshaking?
Answer: Handshaking is used to negotiate the properties of a connection that is being established. Acknowledgments are used to tell the sender that data has been successfully received by the destination during the use of a connection.
Q-3 How many VTP modes are there and what are they?
Answer: Three: Server, Client, and Transparent
Q-4 What are the two types of Trunk encapsulation protocols?
Answer: IEEE 802.1Q and Cisco’s ISL
Q-5 What are the four primary no routable protocols?
Answer: SNA, NetBIOS, DEC LAT, DEC MOP
Q-6 What is the difference between TCP and UDP?
Answer: The primary difference between TCP and UDP is that TCP is a connection oriented protocol and UDP is a connectionless protocol.
Q-7 What is HSRP?
Answer: HSRP, or the Hot Standby Routing Protocol, is a Cisco proprietary protocol that brings routing functionality to end devices that would otherwise not be capable of taking advantage of redundant network connections. HSRP enables a pair of Cisco routers to work together to present the appearance of a single virtual default-gateway to end devices on a LAN segment.
Q-8 What is the difference between a Public IP address and a Private IP address?
Answer: Public address space is a unique address that is assigned to a company. Private address space is not recognized by the Internet and can be used by anyone
within their private network.
Q-9 What does AAA stand for?
Answer: Authentication, authorization, and accounting
Q-10 The H.323 protocol is used for what?
Answer: H.323 is used for multiservice (multimedia) applications, usually in a Voice Over IP environment.
Answer: The Transport layer of the OSI model is responsible for reliable connections.
Q-2 What is the difference between acknowledgments and handshaking?
Answer: Handshaking is used to negotiate the properties of a connection that is being established. Acknowledgments are used to tell the sender that data has been successfully received by the destination during the use of a connection.
Q-3 How many VTP modes are there and what are they?
Answer: Three: Server, Client, and Transparent
Q-4 What are the two types of Trunk encapsulation protocols?
Answer: IEEE 802.1Q and Cisco’s ISL
Q-5 What are the four primary no routable protocols?
Answer: SNA, NetBIOS, DEC LAT, DEC MOP
Q-6 What is the difference between TCP and UDP?
Answer: The primary difference between TCP and UDP is that TCP is a connection oriented protocol and UDP is a connectionless protocol.
Q-7 What is HSRP?
Answer: HSRP, or the Hot Standby Routing Protocol, is a Cisco proprietary protocol that brings routing functionality to end devices that would otherwise not be capable of taking advantage of redundant network connections. HSRP enables a pair of Cisco routers to work together to present the appearance of a single virtual default-gateway to end devices on a LAN segment.
Q-8 What is the difference between a Public IP address and a Private IP address?
Answer: Public address space is a unique address that is assigned to a company. Private address space is not recognized by the Internet and can be used by anyone
within their private network.
Q-9 What does AAA stand for?
Answer: Authentication, authorization, and accounting
Q-10 The H.323 protocol is used for what?
Answer: H.323 is used for multiservice (multimedia) applications, usually in a Voice Over IP environment.
Interview Tips
what is interview
Ah, the technical interview.
Nothing like it.
Not only does it cause anxiety, but it causes anxiety for several
different reasons.
How many people will be asking questions?
>From experience I can tell you there's nothing like walking into a
room and seeing nine people on the other side of the table.
Second, what will you be asked?
You'll sometimes hear people say the questions they were asked in a
technical interview were "easy", which translated means "they
asked me stuff I happened to know".
Sometimes you'll hear people say the questions were "hard", which
translated means "they asked me stuff I didn't know", or "they
asked me about stuff I've never even heard of".
Having been on both sides of the technical interview table, I'd like
to share some tips for those being interviewed.
In doing so, I'll share some of the more memorable interviews I've
been involved in.
No good interviewer expects you to know everything.
The problem is, you're not always going to be interviewed by someone
who's good at it.
Sometimes, the person who's giving you a technical interview was
asked to do it about ten minutes before you showed up.
Maybe they've never interviewed anyone before, or maybe they're
just in a bad mood.
I've heard of technical interviewers where the interviewer derided an
answer, and that's totally unprofessional.
I've had many a job candidate give a bad answer to a question, and my
only response was silence followed by moving on to the next question.
If your interviewer mocks any of your answers, you didn't want to
work there anyway.
None of us know everything.
If you're asked a question you just don't know the answer to,
don't try to BS your way past it.
This is a good opportunity to tell the interviewer how you would
research that particular question.
It's not about knowing everything, it's about being able to find
out anything.
If your interviewer acts like he/she already dislikes you, that's
because they do.
I once worked with a technician who felt threatened by anyone who
applied for a job there, but especially if the applicant had a
professional certification and then had the nerve to know what they
were doing.
This technician participated in a group technical interview where the
applicant was an incredibly bright guy, and had a particular skill that
the department really needed.
Problem was, the technician considered himself "the man" when it
came to that skill.
Recipe for disaster, right?
The applicant fielded four questions from the rest of us flawlessly,
then faced this particular tech for a question.
The threatened tech had a list of questions for the interview, but
decided to ad lib.
Big mistake.
He asked a convoluted question that Rube Goldberg would have been proud
of.
When he was done, the applicant answered:
"You can't do what you just described."
The tech started defending his question, and it became obvious that he
hadn't been able to follow his own question!
The interview went into a bit of a meltdown from there.
Realize right now that there are some unprofessional people out there
giving technical interviews.
Be prepared for it, but remain professional yourself.
Be prepared for a practical technical interview.
The best technical interviewers find a way to get you in front of the
technology you'll be working with.
A great way to quickly find out whether you know what you're talking
about is to ask you to actually perform common and perhaps some
not-so-common tasks.
We can talk about technology and take all the computer-based exams we
want, but it all comes down to performance.
Be prepared to prove you belong on your interview day.
Be professional.
This covers a lot of ground, so let me make a quick list for you.
Show up 15 minutes early.
Nothing makes a technical interviewer more surly than waiting for the
applicant.
Dress for success.
The way you look when you walk into a room leads to your
interviewer's first impression of you.
Don't chew gum during the interview.
Don't be arrogant.
Look, there's nothing wrong with having an ego and acting confident.
I do, and you should.
But don't come into the interview room acting like you're too good
to be there.
Finally, relax.
Easy to say, hard to do?
Not really.
Realize that the majority of interviewers you'll ever meet are going
to be professional about the entire thing.
The world's not going to end if you miss a question.
If you were not qualified on paper for the job, you wouldn't be in
there.
Do not look upon the interview as something negative.
Rather, look at it as an opportunity to prove you know what you're
talking about.
With the proper mental attitude, your technical interview will be a
springboard to the next step in your career!
so guys be prepared and follow the TIP ,i am assuring u not scared with interview u will be cracked........ Arun Kumar
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