From: Voss, David (dvoss@heidrick.com)
Date: Sun Mar 16 2003 - 11:59:49 GMT-3
Okay.. I enabled ppp and then I see the command. Thanks
I'm referring to the following CCO article which states that no peer neigh
is one way to resolve the following issue:
The link between Routers 1 and 2 is 131.108.1.0/24, and demand circuit is
configured between Routers 1 and 2. Router 1 is redistributing Routing
Information Protocol (RIP) routes into OSPF.
Router 1
router ospf 1
redistribute rip subnets
network 131.108.1.0 0.0.0.255 area 1
!
router rip
network 131.108.0.0
Since the link encapsulation type is PPP, both routers install a host route
for the other side of the link as shown below.
Router1#show ip route 131.108.1.2
Routing entry for 131.108.1.2/32
Known via "connected", distance 0, metric 0 (connected, via interface)
Routing Descriptor Blocks:
* directly connected, via BRI1/1
Route metric is 0, traffic share count is 1
Interior Gateway Routing Protocol (IGRP) and RIP are classful routing
protocols, and therefore the network statement in the configuration is for a
classful network of 131.108.0.0. Because of this the host route of
131.108.1.2/32 is considered to be originated by RIP and gets redistributed
into OSPF as an external route as shown below.
Router1#show ip ospf database external 131.108.1.2
OSPF Router with ID (131.108.3.1) (Process ID 1)
Type-5 AS External Link States
LS age: 298
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 131.108.1.2 (External Network Number )
Advertising Router: 131.108.3.1
LS Seq Number: 80000001
Checksum: 0xDC2B
Length: 36
Network Mask: /32
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
When the link goes down the /32 disappears and OSPF understands this as a
change in topology. The demand circuit brings the link up again to propagate
the MAXAGE version of the /32 mask to its neighbor. When the link comes up,
the /32 mask becomes valid again so the LSA age gets reset. Then after the
dead timer of the link kicks in, the link goes down again. This process
repeats itself and the demand circuit link keeps flapping. There are three
ways to solve this problem shown below.
Solution 1: Use the no peer neighbor-route Command
Under the BRI interface that is running demand circuit, configure no peer
neighbor-route. This prevents the /32 mask from being installed. You can use
the configuration shown below on Router 1 only, but we recommend configuring
this command on both sides for consistency.
R1#configure terminal
R1(config)#interface BRI1/1
R1(config-if)#no peer neighbor-route
-----Original Message-----
From: Brian Dennis [mailto:brian@labforge.com]
Sent: Sunday, March 16, 2003 12:26 AM
To: Voss, David; ccielab@groupstudy.com
Subject: RE: Peer Neighbor Route /32
The command has been around since IOS 11.2. Are you sure it's not there?
If you don't have PPP encapsulation turned on the router won't take the
command.
Can you elaborate on the /32 issue bringing up the ISDN line? Are you
referring to an ASBR with an OSPF demand circuit? Also the peer
neighbor-route command is PPP related and isn't related to any "ip ospf"
interface commands.
Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security) CCSI# 98640
brian@labforge.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Voss, David
Sent: Saturday, March 15, 2003 8:02 PM
To: ccielab@groupstudy.com
Subject: Peer Neighbor Route /32
Regarding eliminating /32's over BRI to prevent OSPF from bringing the
line
up.. I understand that one should use
no peer neighbor-route
My IOS does not support this feature. IOS (tm) 2500 Software
(C2500-JOS56I-L), Version 12.1(5)T9
Wondering if anyone has used this command on a serial or ethernet
interface
to eliminate /32's instead of the "ip ospf netw point-to-point" method.
This archive was generated by hypermail 2.1.4 : Sat Apr 05 2003 - 08:51:40 GMT-3