From: John Murphy (jt.murphy@comcast.net)
Date: Sat Mar 05 2005 - 23:57:06 GMT-3
Comments inline
Jongsoo.Kim@Intelsat.com wrote:
>I am sure many of you know about this.
>This is totally news to me. ( I have obvioulsy underestimated the mighty
>RIP!)
>
>As passive interface behaves differently between Rip and EIGRP, so does ip
>summary-address.
>For rip, Ip split-horizon has be to diable for summary-address to be
>advertise, while EIGRP don't care about it.
>
>
I agree that the documentation says this, however in practice it's not
quite so clearcut.... this is on a router running 12.2(15)T12. Example
below....
[R2 --S2/0-]------------[-S2/0 --R4 --S2/0.13-]-------------[-S2/0--R3]
R4#sh ip int Ser2/0.13
Serial2/0.13 is up, line protocol is up
Internet address is 172.10.43.4/24
Broadcast address is 255.255.255.255
Address determined by non-volatile memory
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is disabled
Multicast reserved groups joined: 224.0.0.14 224.0.0.17 224.0.0.1
224.0.0.2
224.0.0.22 224.0.0.13 224.0.0.9
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Local Proxy ARP is disabled
Security level is default
Split horizon is enabled <<<<<<<<<<<<<<<<<<<<<<<<<<<< Split Horizon
is enabled
I added three /32 loopbacks on R4...
!
interface Loopback234
ip address 172.10.200.234 255.255.255.255
!
interface Loopback235
ip address 172.10.200.235 255.255.255.255
!
interface Loopback236
ip address 172.10.200.236 255.255.255.255
!
I then configured the summary on Ser2/0.13
interface Serial2/0.13 point-to-point
ip address 172.10.43.4 255.255.255.0
ip pim dense-mode
ip summary-address rip 172.10.200.0 255.255.255.0
frame-relay interface-dlci 403
ip rsvp bandwidth 25 20
!
And on R3....
R3#ship rip
172.10.0.0/16 is variably subnetted, 19 subnets, 6 masks
R 172.10.200.0/24 [120/1] via 172.10.43.4, 00:00:06, Serial2/0
R 172.10.25.0/29 [120/1] via 172.10.43.4, 00:00:06, Serial2/0
R 172.10.25.64/26 [89/1] via 172.10.43.4, 00:00:06, Serial2/0
It's just another IGP, don't let it psych you out....
jm
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