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AD of EIGRP summarization route

lehpoh
Level 1
Level 1

The setup of my customer live network is as follows:

R2

|

|

switch--------R1--------internet

|

|

|

R3

R1, R2 and R3 is running EIGRP. I want R1 to inject default route to R2 and R3, so I configure "ip summary-address eigrp 50 0.0.0.0 0.0.0.0" on R1 interface which connects to the switch.

When I do a show ip route on both R2 and R3, why the AD for the default route is 90 instead 5? I thought AD for EIGRP summary route is 5?

6 Replies 6

mschooley
Level 1
Level 1

not sure why you're using the summary address command to inject a default route, eigrp will redistribute default automatically, so if you have ip route 0.0.0.0 0.0.0.0 on router 1 configured, that is probably where the default is being learned from.

Do you mean that as long as I have this statement, "ip route 0.0.0.0 0.0.0.0 next-hop" configured in R1, R2 and R3 will automatically have default route installed through EIGRP?

mschooley
Level 1
Level 1

although I would like someone to clarify the ad of 5, I don't remember having ever heard that, but looked up on web page and verified it, however if I look at some of the address aggregation examples in doyle's book vol 1, it shows the ad of the aggregated routes as 90, not 5, can someone clarify?

AD is only local to a router it is not passed on to other boxes

mark-obrien
Level 4
Level 4

The "ip summary-address eigrp" command creates a route pointing the summary address to the Null interface. The AD of the summary address, then, is the AD of this static route to Null. This means that the router will believe the route to Null over another EIGRP route to the same summary address. If you want the router to believe the summary from another router, assign an AD greater than 90 to the summary route.

HTH

Mark

yes you just need ip route 0.0.0.0 0.0.0.0 on router 1, no if it was igrp, you would need a default network command, or ospf a default originate command, but best I can remember, eigrp automatically distributes default

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