From: Robert Caamano (rcaamano@xxxxxxx)
Date: Wed Jun 16 1999 - 21:15:54 GMT-3
Ben,
The answer to your question is this:
By default OSPF treats Loopback interfaces differently than a regular
interface in that it
considers it a stub host. You will notice that you have a route that has a
/32 mask
(172.16.1.161/32). This address is the primary Loopback address and the
only Loopback address
advertised by default. OSPF advertises it this way to identify that it is a
stub host interface.
Here's how you make it work
type the following
#conf t
(config)#int lo0
(config-if)#ip ospf netw point-to-point
This will make ospf see the loopback interface as a point to point network
instead of a stub host
and will then allow normal rules for secondary interface advertizment apply.
-----Original Message-----
From: Ben Rife <brife@bignet.net>
To: Rick Burts <burts@ccci.com>
Cc: ccielab@groupstudy.com <ccielab@groupstudy.com>
Date: Wednesday, June 16, 1999 11:50 AM
Subject: Re: OSPF and Loopback intf.
>I just can't get this to work. My secondary networks on the loopback on
>r2520 will not show up in the route table of r2503. Here is my OSPF and
>Loopback configs....
>
>Router 2503
>
>r2503#sh run
>Building configuration...
>
>Current configuration:
>!
>version 11.2
>no service password-encryption
>no service udp-small-servers
>no service tcp-small-servers
>!
>hostname r2503
>!
>!
>no ip domain-lookup
>isdn switch-type basic-ni1
>!
>interface Ethernet0
> ip address 192.168.40.2 255.255.255.0
>!
>interface Serial0
> ip address 172.16.1.146 255.255.255.240
>!
>interface Serial1
> no ip address
> clockrate 64000
>!
>interface BRI0
> no ip address
> isdn spid1 0835866101 8358661
> isdn spid2 0835866301 8358663
>!
>router ospf 10
> network 172.16.1.146 0.0.0.0 area 0
>!
>no ip classless
>!
>!
>line con 0
>line aux 0
>line vty 0 4
> login
>!
>end
>
>
>
>
>Router 2520
>
>
>r2520#sh run
>Building configuration...
>
>Current configuration:
>!
>version 11.2
>no service password-encryption
>no service udp-small-servers
>no service tcp-small-servers
>!
>hostname r2520
>!
>!
>no ip domain-lookup
>!
>interface Loopback0
> ip address 172.16.1.225 255.255.255.240 secondary
> ip address 172.16.1.193 255.255.255.240 secondary
> ip address 172.16.1.129 255.255.255.240 secondary
> ip address 172.16.1.161 255.255.255.240
>!
>interface Ethernet0
> no ip address
>!
>interface Serial0
> no ip address
> shutdown
> no fair-queue
>!
>interface Serial1
> no ip address
> shutdown
> clockrate 56000
>!
>interface Serial2
> ip address 172.16.1.145 255.255.255.240
> bandwidth 1544
> clockrate 56000
>!
>interface Serial3
> no ip address
> shutdown
>!
>interface BRI0
> no ip address
> shutdown
>!
>router ospf 10
> network 172.16.1.161 0.0.0.0 area 0
> network 172.16.1.225 0.0.0.0 area 0
> network 172.16.1.129 0.0.0.0 area 0
> network 172.16.1.193 0.0.0.0 area 0
> network 172.16.1.145 0.0.0.0 area 0
>!
>no ip classless
>lat service ABLE password CISCO
>!
>!
>line con 0
>line aux 0
>line vty 0 4
> login
>!
>end
>
>
>
>
>Route table of r2503
>
>r2503#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
>
>C 192.168.40.0/24 is directly connected, Ethernet0
> 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
>O 172.16.1.161/32 [110/65] via 172.16.1.145, 00:05:15, Serial0
>C 172.16.1.144/28 is directly connected, Serial0
>
>
>
>Thanks for any help you can provide,
>
>Ben Rife
>CCIE Candidate
>
>
>
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