From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Tue Jan 23 2007 - 01:38:37 ART
Here is a post I made a few months back on this subject:
The behavior of point-to-multipoint is to advertise each end-point out
as a /32 and suppress the advertisement of the network itself.
Point-to-multipoint advertised the end points to overcome possible
reachability issues between devices that are on the same logical subnet
but do not have direct communication (i.e. spoke to spoke communication
in a hub and spoke environment). The OSPF point-to-multipoint and
loopback network types do not advertise the network itself but advertise
a host route for each end-point. This is as per the RFC.
If you want to suppress the /32s and advertise only the network, you
would need to use an OSPF network type other than point-to-multipoint or
configure the network to be in its own OSPF area. After the network is
put in its own OSPF area, use the area range command to summarize the
/32s so other routers only see the summarized route.
HTH,
Brian Dennis, CCIE4 #2210 (R&S/ISP-Dial/Security/SP)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
johngibson1541@yahoo.com
Sent: Monday, January 22, 2007 7:28 PM
To: ccielab@groupstudy.com
Subject: ip ospf network point-to-multipoint non-broadcast, result is
that only /32 routes are advertised out
Did any one have the same surprise ? Or is that my IOS version's bug ?
I know point-to-multipoint adds extra /32 routes to 2 adjacent routers.
Nothing wrong. Still reachable to every interface. Just strange to me.
But I didn't know when "non-broadcast" is added, ONLY /32 routes are
advertised out to all other ospf routers.
I once used 12.3(1a) with 2514 just to discover that nssa
default-information originate doesn't work on that particular version.
Now I use 12.3(17a). Don't know if there is a problem.
John
This archive was generated by hypermail 2.1.4 : Thu Feb 08 2007 - 23:46:57 ART