From: Glen Lavers (glavers@xxxxxxxxx)
Date: Tue Apr 17 2001 - 19:13:05 GMT-3
I just tried it and it works, but you have to disable split-horizon on s0.
Here's an example and debugs:
-Glen
R1#sh run
!
hostname R1
!
!
ip subnet-zero
!
!
interface Ethernet0/0
ip address 172.16.77.130 255.255.255.128
no ip directed-broadcast
!
interface Serial0/0
ip address 172.16.66.5 255.255.255.128 secondary
ip address 172.16.66.4 255.255.255.0
no ip directed-broadcast
no ip split-horizon
no ip mroute-cache
no fair-queue
!
R3#sh run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname R3
!
!
ip subnet-zero
!
!
!
interface Ethernet0/0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0/0
ip address 172.16.66.7 255.255.255.128 secondary
ip address 172.16.66.6 255.255.255.0
no ip directed-broadcast
no ip mroute-cache
clockrate 64000
Debugs: notice at first it only sends subnet 172.16.66.0 out e0/0 the once
split-horizon is disabled it sends out 172.16.77.128 out s0/0:
00:47:38: IGRP: sending update to 255.255.255.255 via Serial0/0
(172.16.66.4)
00:47:38: IGRP: Update contains 0 interior, 0 system, and 0 exterior routes.
00:47:38: IGRP: Total routes in update: 0 - suppressing null update
00:48:53: IGRP: sending update to 255.255.255.255 via Ethernet0/0
(172.16.77.130
)
00:48:53: subnet 172.16.66.0, metric=8476
00:48:53: IGRP: Update contains 1 interior, 0 system, and 0 exterior routes.
00:48:53: IGRP: Total routes in update: 1
00:48:53: IGRP: sending update to 255.255.255.255 via Serial0/0
(172.16.66.4)
00:48:53: IGRP: Update contains 0 interior, 0 system, and 0 exterior routes.
00:48:53: IGRP: Total routes in update: 0 - suppressing null update
R1#
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int s0/0
R1(config-if)#no ip spl
R1(config-if)#^Z
R1#
00:49:27: %SYS-5-CONFIG_I: Configured from console by console
R1#
R1#
00:50:13: IGRP: sending update to 255.255.255.255 via Ethernet0/0
(172.16.77.130
)
00:50:13: subnet 172.16.66.0, metric=8476
00:50:13: IGRP: Update contains 1 interior, 0 system, and 0 exterior routes.
00:50:13: IGRP: Total routes in update: 1
00:50:14: IGRP: sending update to 255.255.255.255 via Serial0/0
(172.16.66.4)
00:50:14: subnet 172.16.66.0, metric=8476
00:50:14: IGRP: Update contains 1 interior, 0 system, and 0 exterior routes.
00:50:14: IGRP: Total routes in update: 1
00:50:14: IGRP: sending update to 255.255.255.255 via Serial0/0
(172.16.66.5)
00:50:14: subnet 172.16.77.128, metric=1100
00:50:14: subnet 172.16.66.0, metric=8476
00:50:14: IGRP: Update contains 2 interior, 0 system, and 0 exterior routes.
00:50:14: IGRP: Total routes in update: 2
R1#
R1#
R3#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate
default
U - per-user static route, o - ODR
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
I 172.16.77.128/25 [100/8576] via 172.16.66.5, 00:01:09, Serial0/0
C 172.16.66.0/25 is directly connected, Serial0/0
C 172.16.66.0/24 is directly connected, Serial0/0
R3#
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Glen Lavers
Sent: Tuesday, April 17, 2001 11:43 PM
To: Wang, Roger; ccielab@groupstudy.com
Subject: RE: IGRP route advertisement
RE: IGRP route advertisementWhat I meant is try placing 172.16.66.5/25 for
example on s0 as a sec, as well as placing a /25 sec on the other end of the
serial line. This should carry the e0 /25 route right through to the routing
table of the router hanging off s0.
Glen
-----Original Message-----
From: Wang, Roger [mailto:Roger@inteqnet.com]
Sent: Tuesday, April 17, 2001 9:19 PM
To: 'Glen Lavers'; ccielab@groupstudy.com
Subject: RE: IGRP route advertisement
I've tried that. The network of the secondary IP address (using, say,
172.16.70.4 /25) gets advertised, but somehow 172.16.77.4/25 still did not.
Rog
> -----Original Message-----
> From: Glen Lavers [mailto:glavers@cisco.com]
> Sent: Tuesday, April 17, 2001 3:14 PM
> To: Wang, Roger; ccielab@groupstudy.com
> Subject: RE: IGRP route advertisement
>
>
> You can place a secondary address with a /25 on the serial
> int, it should
> then advertise both /24 and /25 addresses. Give it a try, I
> know I've used
> this technique the otherway around for making a poorly
> addressed VLSM to
> FLSM topo work.
> Cheers,
> Glen
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Wang, Roger
> Sent: Tuesday, April 17, 2001 8:22 PM
> To: 'ccielab@groupstudy.com'
> Subject: IGRP route advertisement
>
>
> Hi, all,
>
> I have searched high and low in the archive and can't seem to
> find anything
> about it...
>
> I have a question about IGRP route advertisement. We all
> know that the
> advertisements from IGRP are only with the mask of the interface:
>
> 172.16.77.4/25--e0(R4)s0--172.16.66.4/24
>
> R4 is running IGRP. Is there way so that the /25 subnet (e0) can be
> advertised out interface s0 (on /24 subnet)? The other end of s0 is a
> router running both IGRP and OSPF where redistribution occurs.
>
> Thanks,
>
> Rog
> **Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
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