RE: Split-horizon mystery

From: Cameron, John (johcamer@cisco.com)
Date: Thu Feb 27 2003 - 09:58:59 GMT-3


Hunt,

For EIGRP you do not need to enable spilt-horizon because it is on
by default on all interfaces - even physical. The command that you
have under RTC interface is for a DV protocol (RIP or IGRP) - it doesn't
apply to EIGRP in this scenario. So yes.. EIGRP is different in the fact
that it's on by default for all interfaces physical, p2p, and p2m.

HTH,
JDC

-----Original Message-----
From: Hunt Lee [mailto:huntl@webcentral.com.au]
Sent: Thursday, February 27, 2003 2:20 AM
To: 'ccielab@groupstudy.com'
Subject: Split-horizon mystery

Hi Group,

Does anyone know when one should use "ip split-horizon" for EIGRP?

      RTD
     /
RTA---- RTB
      \
        RTC

RTA, RTB & RTD are using OSPF, while RTA & RTC are both using EIGRP...

RTA & RTC are point-to-point, while..

RTA, RTB & RTD are point-to-multipoint

On the solutions, I was told that I need to use "ip split-horizon" on RTC
outgoing interface (to RTA), why??? I thought we only need to use this
command on the hub if it is point-to-multipoint sub-interface...

anyway, here's the config:-

On RTC:-

interface Serial0
 ip address 137.20.200.18 255.255.255.240
 ip nat outside
 encapsulation frame-relay
 ip split-horizon <------ Do we need this???
 no ip mroute-cache
 keepalive 15
 no fair-queue
 frame-relay lmi-type ansi

router eigrp 10
 network 137.20.0.0
 no auto-summary

And on RTA:-

interface Serial0.1 multipoint
 ip address 137.20.100.34 255.255.255.224
 ip ospf network point-to-multipoint
 frame-relay de-group 1 502
 frame-relay map ip 137.20.100.33 502 broadcast
 frame-relay map ip 137.20.100.35 503 broadcast
!
interface Serial0.2 point-to-point
 bandwidth 2000
 ip address 137.20.200.17 255.255.255.240
 frame-relay interface-dlci 504

router eigrp 10
 redistribute ospf 10 metric 2000 100 255 1 1500
 passive-interface BRI0
 passive-interface Ethernet0
 passive-interface Serial0.1
 passive-interface Serial1
 network 137.20.0.0
 no auto-summary
 no eigrp log-neighbor-changes

      
Any help / ideas would be greatly appreciated.

Regards,
Hunt



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