ROUTE AUTHENTICATION WITH EIGRP

Using Route Authentication with EIGRP

Corp#config t
Corp(config)#int s0/0/1
Corp(config-if)#ip authentication mode eigrp 10 md5
Corp(config-if)#ip authentication key-chain eigrp 10 todd
Corp(config-if)#exit
Corp(config)#key chain todd
Corp(config-keychain)#key 1
Corp(config-keychain-key)#key-string 1234567890
Corp(config-keychain-key)#accept-lifetime 04:00:00 Jan 14 2008 infinite
Corp(config)#send-lifetime 04:00:00 Jan 14 2008 04:50:00 Jan 14 2008

interface interface configure an interface type and enter interface configuration mode
ip authentication mode eigrp AS md5 enable MD5 authentication in EIGRP route update packets
ip authentication key-chain eigrp as key-chain enable authentication of EIGRP packets
key chain name identify the key chain
key number In key chain configuration mode, identify the key number
key-string text In key chain key configure mode, identify the key string
accept-lifetime start-time (optional) specify the time period during which the key can be received
send-lifetime start-time (optional) specify the time period during which the key can be sent

IMPORTANT - EIGRP automatically summarizes networks at the classful boundary.A poorly designed network with discontiguous subnets could have problems with connectivity if the summarization feature is left on. For instance, youcould have two routers advertise the same network—172.16.0.0/16—when in fact they wanted to advertise two different networks—172.16.10.0/24 and 172.16.20.0/24. Recommended practice is that you turn off automatic summarization if necessary, use the ip summary-address command, and summarize manually what you need to.

Router(config)#interface fastethernet 0/0 Enters interface configuration mode.
Router(config-if)#ip summary-address eigrp 100 10.10.0.0 255.255.0.0 75 Enables manual summarization for EIGRP autonomous system 100 on this specific interface for the given address and mask. An administrative distance of 75 is assigned to this summary route. The administrative-distance argument is optional in this command.Without it, an administrative distance of 5 is automatically applied to the summary route.