From: Bit Gossip (bit.gossip@chello.nl)
Date: Thu Aug 16 2007 - 01:59:34 ART
Hi NET,
what I know for sure is that RIP v2 has the next-hop field which in case of
broadcast media is set to the router closest to the destination: in your lab
this is R1. This is similar to the OSPF forwarding-address.
Your test seems to show that instead EIGRP doesn't have this feature but I
not sure about that.
Thanks,
bit.
----- Original Message -----
From: "NET HE" <he_net@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Wednesday, August 15, 2007 3:34 AM
Subject: Split-horizon rule while redistributing?
> Hi there,
>
> Today I tried a couple of configurations to pratise split-horizon rule
> while redistributiing between routing protocols, results are as follow. It
> would be very appreciated if someone can explain me why?
>
> (IOS 12.4)
> Topology:
>
> Router1 has loop0 (10.0.0.1 255.255.255.255) and fa0/0 (172.16.1.1
> 255.255.255.0)
>
> Router2 has fa0/0 (172.16.1.2 255.255.255.0)
>
> Router3 has loop0 (10.0.0.3 255.255.255.255) and fa0/0 (172.16.1.3
> 255.255.255.0)
>
> All fa0/0s are connected to an ethernet segment.
>
> Case 1:
>
> Router1 configuration
> Router eigrp 100
> no auto
> network 172.16.0.0
> network 10.0.0.0
>
> Router2 configuration
> Router eigrp 100
> no auto
> network 172.16.0.0
> default-metric 10000 10 1 255 1500
> redistribute eigrp 10
>
> Router eigrp 10
> no auto
> network 172.16.0.0
> default-metric 10000 10 1 255 1500
> redistribute eigrp 100
>
> Router3 configuration
> Router eigrp 10
> no auto
> network 172.16.0.0
> network 10.0.0.0
>
> I don't have to disable split-horizon at all at fa0/0 on router 2, router1
> sees 10.0.0.3 via 172.16.1.2 (next-hop) and router1 sees 10.0.0.1 via
> 172.16.1.2 (next-hop).
>
> But when eigrp 10 is replaced by RIP, and redistribution happens betwen
> eigrp 100 and RIP, I have to disable split-horizon @Route2 for RIP so that
> Router3 can see 10.0.0.1. Here are questions:
>
> 1)When the distribution happens between 2 different eigrp AS, @ Router1
> route 10.0.0.3 and @Router2 route 10.0.0.1 both point to 172.16.1.2 as
> next-hop address, but When the distribution happens between eigrp and RIP,
> @Router1 route 10.0.0.3 which is redistributed from RIP is via 172.16.1.2
> (next-hop) but @ Router3 route 10.0.0.1 which is redistributed from eigrp
> 100 is via 172.1.1.1 (next-hop), why are they different in terms of
> next-hop?
>
> 2)What's the split-horizon rule while doing redistribution
>
> Thanks.
>
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This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:11 ART