Simple way / command that can tell me the (EIGRP) route root source?

[jmaxwellUSAF]

Hello. Simple quick question...

When I'm trying to find the source of a route (especially EIGRP), my method is to laboriously

sh ip route x.x.x.x

then get that next hop data, then SSH into the next box and repeat until I reach the source.

Is there some simple way or command that can tell me the root source of the routing info?

Thank you!

[David Ruess · Accepted solution]

Try

show ip eigrp topology table x.x.x.x/nn

*should give you a filed of Originating Router

The originating router is based on the RID so that's what it will give you. If you don't have that RID/IP advertised into the network you probably wont be able to log into the router based off that. But as long as you know what RID belongs to what router then you should be able to find it easy.

-David

[MHM Cisco World]

EIGRP not like OSPF so the originate router not see in table. 

[David Ruess]

Newer code should show it. I just ran it on my equipment and it shows the originating router.

[MHM Cisco World]

Newer Code but same RFC. 
let give you example in the hub-spoke we must config

no ip next-hop-self

<<-why ? because the EIGRP change the origin of prefix, while the OSPF not (this only in OSPF of same area in different area or different AS the origin change) 

[David Ruess]

I think you are confusing terms. Next hop and Originating router are NOT the same. I did see a flaw in my command though. This only works for routes redistributed into EIGRP (External).

@jmaxwellUSAF for internal routes you can check the hop count. See below it gives the hop count of how far away the route was introduced into the network.

https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/16406-eigrp-toc.html

-David

[MHM Cisco World]

Yes, I know this only appear for external and only appear in router redistribute prefix into EIGRP 
this info. disappear in other router.

[MHM Cisco World]

do traceroute and you end in router that connect or static redistribute the prefix 

[jmaxwellUSAF]

This is good idea, but usually pings are disabled on intermediate devices in this LAN.

[MHM Cisco World]

then you need telnet to see where is the origin of this prefix