EIGRP Tuning and Troubleshooting

EIGRP Tuning and Troubleshooting

1. network topolgy

2. Network topology

   • The bandwidths of the serial links used in this topology help explain the calculation of the routing protocol metrics and the process of best path selection
     • The bandwidth commands on the serial interfaces were used to modify the default bandwidth of 1,544 kb/s.

3. EIGRP Automatic Summarization

   • Route summarization allows a router to group networks together and advertises them as one large group using a single, summarized route. The ability to summarize routes is necessary due to the rapid growth of networks
   • A border router is a router that sits at the edge of a network. This router must be able to advertise all of the known networks within its routing table to a directly-connected network router or ISP router.
   • Summarization decreases the number of entries in routing updates and lowers the number of entries in local routing tables.

4. Propagating a Default Static Route

   • Using a static route to 0.0.0.0/0 as a default route is not routing protocol-dependent.
   • The "quad zero" default static route can be used with any currently supported routing protocols. The default static route is usually configured on the router that has a connection to a network outside the EIGRP routing

5. EIGRP Bandwidth Utilization

   • IPV4
     • EIGRP uses only up to 50 percent of an interface’s bandwidth for EIGRP information.
     • This prevents the EIGRP process from over-utilizing a link and not allowing enough bandwidth for the routing of normal traffic.
     • Use the ip bandwidth-percent eigrp command to configure the percentage of bandwidth that can be used by EIGRP on an interface.
   • IPV6
     • To configure the percentage of bandwidth that can be used by EIGRP for IPv6 on an interface, use the ipv6 bandwidth-percent eigrp command in interface configuration mode.
     • To restore the default value, use the no form of this command. Router(config-if)# ipv6 bandwidth-percent eigrp as-number percent

6. Hello Intervals and Hold Times with EIGRP

   • IPV4
     • EIGRP uses a lightweight Hello protocol to establish and monitor the connection status of its neighbor.
     • The hold time tells the router the maximum time that the router should wait to receive the next Hello before declaring that neighbor as unreachable.
     • Hello intervals and hold times are configurable on a per-interface basis and do not have to match with other EIGRP routers to establish or maintain adjacencies.
   • IPV6
     • EIGRP for IPv6 uses the same Hello interval and hold times as EIGRP for IPv4.

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