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Posts Tagged ‘eigrp’

 

    Passive-interface 将一个接口指定为被动接口！然而这个命令在RIP和OSPF/EIGRP中却有不同的表现。

 

    下面我们通过实验来解析一下这个命令。

实验所用的TOP还是上一篇日志用到的TOP。IP规划也同上面一样。
上一篇日志的地址为：（CCNP 642-902 Distribute-list in the RIP.）http://yangbo.name/archives/1155.html

因为本站是的VPS是在国外的，且支持IPv6访问。如果你在拥有IPv6接入我建议你使用IPv6方式访问，一个是免费、二个是IPv6的出国速度也比IPv4较快一点点（教育网）。

 

Passive-interface of RIP

Passive-interface of EIGRP

Passive-interface of OSPF

 总结

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今天群里在讨论这么一个拓扑图。

图中共有4个路由器：
R1、R2、R4（上面的3个路由器处于Eigrp AS100中。
R1、R3、R4（下面的3个路由器处于Eigrp AS200中。

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Exam Description

Troubleshooting and Maintaining Cisco IP Switched Networks (TSHOOT 642-832) is a qualifying exam for the Cisco Certified Network Professional CCNP®, certification. The TSHOOT 642-832  exam will certify that the successful candidate has important knowledge and skills necessary to (1) plan and perform regular maintenance on complex enterprise routed and switched networks and (2) use technology-based practices and a systematic ITIL-compliant approach to perform network troubleshooting.

Exam Topics

The following information provides general guidelines for the content likely to be included on the exam. However, other related topics may also appear on any specific delivery of the exam. In order to better reflect the contents of the exam and for clarity purposes the guidelines below may change at any time without notice.

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Exam Description

The Implementing Cisco IP Routing (ROUTE 642-902) is a qualifying exam for the Cisco Certified Network Professional CCNP®, Cisco Certified Internetwork Professional CCIP®, and Cisco Certified Design Professional CCDP® certifications. The ROUTE 642-902 exam will certify that the successful candidate has the knowledge and skills necessary to use advanced IP addressing and routing in implementing scalable and secure Cisco ISR routers connected to LANs and WANs.  The exam also covers configuration of secure routing solutions to support branch offices and mobile workers.

Exam Topics

The following information provides general guidelines for the content likely to be included on the exam. However, other related topics may also appear on any specific delivery of the exam. In order to better reflect the contents of the exam and for clarity purposes the guidelines below may change at any time without notice.

Implement an EIGRP based solution, given a network design and a set of requirements

• Determine network resources needed for implementing EIGRP on a network
• Create an EIGRP implementation plan
• Create an EIGRP verification plan
• Configure EIGRP routing
• Verify EIGRP solution was implemented properly using show and debug commands
• Document results of EIGRP implementation and verification

Implement a multi-area OSPF Network, given a network design and a set of requirements

• Determine network resources needed for implementing OSPF on a network
• Create an OSPF implementation plan
• Create an OSPF verification plan
• Configure OSPF routing
• Verify OSPF solution was implemented properly using show and debug commands
• Document results of OSPF implementation and verification plan

Implement an eBGP based solution, given a network design and a set of requirements

• Determine network resources needed for implementing eBGP on a network
• Create an eBGP implementation plan
• Create an eBGP verification plan
• Configure eBGP routing
• Verify eBGP solution was implemented properly using show and debug commands
• Document results of eBGP implementation and verification plan

Implement an IPv6 based solution, given a network design and a set of requirements

• Determine network resources needed for implementing IPv6 on a network
• Create an IPv6 implementation plan
• Create an IPv6 verification plan
• Configure IPv6 routing
• Configure IPv6 interoperation with IPv4
• Verify IPv6 solution was implemented properly using show and debug commands
• Document results of IPv6 implementation and verification plan

Implement an IPv4 or IPv6 based redistribution solution, given a network design and a set of requirements

• Create a redistribution implementation plan based upon the results of the redistribution analysis
• Create a redistribution verification plan
• Configure a redistribution solution
• Verify that a redistribution was implemented
• Document results of a redistribution implementation and verification plan
• Identify the differences between implementing an IPv4 and IPv6 redistribution solution

Implement Layer 3 Path Control Solution

• Create a Layer 3 path control implementation plan based upon the results of the redistribution analysis
• Create a Layer 3 path control verification plan
• Configure Layer 3 path control
• Verify that a Layer 3 path control  was implemented
• Document results of a Layer 3 path control implementation and verification plan
• Implement basic teleworker and branch services
• Describe broadband technologies
• Configure basic broadband connections
• Describe basic VPN technologies
• Configure GRE
• Describe branch access technologies

As with most other routing protocols, the best path to a destination is the path with the lowest metric. EIGRP has the ability to use several variables to compute the metric to a destination network. The first five listed above are those variables: bandwidth, delay, reliability, load, and MTU. Only bandwidth and delay are used by default. It is highly recommended that the defaults be maintained, because using other variables can result in unknown problems in your network.

The values of bandwidth and delay are determined from the bandwidth and delay values associated with the router interfaces. There are default values, but the values can be changed per interface with the bandwidth and delay subinterface commands.

The formula for computing EIGRP metrics follows:

Metric – {[K1 * Bandwidth + (K2 * Bandwidth)/(256 – Load) + K3 * Delay] * [K5/(Reliability + K4)]} * 256

The default K-values follow: K1 = 1; K2 = 0; K3 = 1; K4 = 0; K5 = 0; therefore, the metric formula can be simplified to:

Metric = (Bandwidth + Delay) * 256

Bandwidth = 10000000/Minimum bandwidth along path; and Delay = Sum of delays along path.

Therefore, the final metric formula becomes:

([10000000/Minimum bandwidth] + Sum of delay/10) * 256

Note: Formula uses the bandwidth in kilobits per second and delay as configured on the interface, which is in microseconds.

Metric example:

In this example, the total cost (metric) for Router_A to get to Network A through Router_B would be:

Minimum bandwidth = 128kbps
Total delay = 100 + 100 + 1000 = 1200/10 ms

([10000000/128] + 1200/10) * 256 = 20030720

The total cost to the same destination through Router_C follows:

Minimum bandwidth = 512kbps
Total delay = 1000 + 100 + 100 = 1200/10 ms

([10000000/512] + 1200/10) * 256 = 5030720

The path through Router_C has the lowest cost. Router_A would, therefore, choose the path through Router_C as the best path and put it in its routing table. This path would then be known as the successor (explained later).

In the above topology, the metric of Router_B to Network A would be 307200. Router_C would also have a metric of 307200 to Network A.

http://www.cisco.com/web/learning/le31/le20/ssat/cim/tac_eigrp.html

 

Detailed Information

In this module, you will learn the basic concepts behind EIGRP. You will also do hands-on Configuration Labs to learn some fundamental concepts of EIGRP, and a Challenge Lab to test your troubleshooting knowledge.

Objectives:

At the end of this tutorial, you will be able to:

• Describe the Reliable Transport Protocol and its function in EIGRP.
• Summarize the neighbor discovery and recovery processes.
• Discuss the process of EIGRP metric calculation and list the variables used.
• Describe how EIGRP determines which paths are loop free.
• Describe the process used to clear bad routes from EIGRP routing tables.
• Describe the query process used to find paths to lost destinations.
• Describe address summarization.
• Summarize the administrative distance used by EIGRP to select routes.
• Describe redistribution.
• Discuss load balancing, over both equal- and unequal-cost paths.
• Describe the three approaches to configuring default routing.

Labs(5):

• Configuration Lab: Configuration, Updates and Acknowledgements, and Debugging
• Configuration Lab: Load Balancing with Variance
• Configuration Lab: Redistribution
• Configuration Lab: Redistribution with an Autonomous System
• Challenge Lab: EIGRP

DUAL  Diffusing Update Algorithm (DUAL),

EIGRP, on the other hand, builds a topology table from information it learns from each of its neighbors. The information sent by EIGRP is nonperiodic and contains only new information. Using the Diffusing Update Algorithm (DUAL), EIGRP then chooses a best path (successor) and alternate loop-free paths (feasible successors) that allow for fast convergence. This information is kept in a topology table separate from the routing table. Upon losing a route to a destination, EIGRP looks for feasible successors in its topology table. If a feasible successor does exist, EIGRP begins using it immediately. If no feasible successors exist, EIGRP queries its neighbors.

For all the above to be accomplished, the components of EIGRP must provide:

• Reliable transport mechanism
• Neighbor discovery/recovery process, which allows EIGRP routers to discover and track other EIGRP speaking routers that are on directly connected networks; part of this process must be done reliably (guaranteed)
• A way to discover which paths are loop free
• A process to clear bad routes from the topology table of all routers on the network
• A process for querying neighbors to find paths for lost destinations

 

 

Reliable Transport Protocol (可靠传输协议）
  1.EIGRP updates and hellos are destined to the multicast address 224.0.0.10.

  2.Protocol Number:88

EIGRP uses multiple packet types for reliable transport, all of which are identified by protocol number 88 in the IP header.

Hello packets are used to discover and recover neighbors. They are multicast and use unreliable delivery (no acknowledgment necessary).

Acknowledgments are used for reliable delivery and are always unicast.

Updates are used to convey route information. Updates are transmitted only when there is a change in the topology; they contain only the changed information, and they are sent only to routers that require the information. If only one router requires the update information, the updates are unicast; otherwise the updates are multicast. Updates use reliable delivery.

Queries and replies are used by DUAL. Queries can be multicast or unicast, and replies are always unicast. Queries and replies use reliable delivery.

Question: Fill in the blanks:
Each EIGRP neighbor receiving a ______ packet will ______ an acknowledgment.

a. unicast, broadcast

b. broadcast, unicast

c. multicast, unicast

d. unicast, multicast

 

When a router receives the hello packet from a new neighbor, EIGRP attempts to exchange routing updates with the neighbor. The updates contain all routes known by the sending routers and the metrics of those routes. When an EIGRP router receives updates from its neighbors, it builds a second table, the topology table, from which it builds a routing (forwarding) table. The topology table contains information needed to build a set of metrics and next hops to each reachable network, including:

• Lowest bandwidth on the path to the destination
• Total delay
• Path reliability
• Path loading
• Minimum-path maximun transmission unit (MTU)
• Feasible distance
• Reported distance
• Route source

 

Question: How can an EIGRP packet be identified by looking at the IP header? (choose all that apply)

  a. Header will have User Datagram Protocol (UDP) Port 88

  b. Header will have TCP Port 88

  c. Header will have destination address of 224.0.0.10

  d. Header will have IP protocol number 88

  e. None of the above

 

 

 

配置EIGRP的基本步骤：
1.

R2(config)#router eigrp ?
  <1-65535>  Autonomous system number  启动EIGRP

R2(config)#network network-number [wildcard-mask]  宣告参与EIGRP的网络

R2(config)#auto-summary / no auto-summary 启用和打开自动汇总功能。默认为打开。

R2(config-if)# ip summary-address eigrp [as-number] [address] [mask] 在接口模式下手工汇总。

 

R2(config-router)#variance ?
  <1-128>  Metric variance multiplier 设置不等价的负载均衡为多少条。

R2(config-router)#eigrp stub ?
  connected     Do advertise connected routes
  receive-only  Set IP-EIGRP as receive only neighbor
  static        Do advertise static routes
  summary       Do advertise summary routes
  <cr>

EIGRP区域类型设置。

在hub-spoke网络中使用，提高路由稳定性，stub路由器向邻居汇报它为stub router,邻居不查询stub router,缺省配置为connected和summary

connected: 指定该路由器可以把和它直接相连的网络信息传递给它的邻居，这个选项默认是开启的。

receive-only : 不能和其它3个参数(connected,static,summary）一起使用。只接收从邻居路由器发送来的信息。

static ： 把静态路由信息传递给它的邻居。

summary：把汇总路由信息传递给它的邻居，这个选项默认是开启的。