From: Justin Menga (Justin.Menga@xxxxxxxxxxxxxxxxxx)
Date: Wed Feb 07 2001 - 06:59:17 GMT-3
OK - the default OSPF interface type for physical frame relay interfaces and
multipoint frame relay subinterfaces is NON_BROADCAST. So if you can't
change it - you're stuck with it. If you can't use frame map, you're stuck
with Inverse ARP.
So, with OSPF Non Broadcast, you must define neighbors on at least the hub
router. This then sets up unicast OSPF adjacencies. Your hub will speak to
your spokes quite happily using Inverse ARP.
The problem comes with routes that are learned via spoke sites that are then
advertised to other spokes. The next hop address is set to the originating
spoke, hence you have a situation where one spoke needs to send packets
directly to another spoke. Typically, to get this working you use frame
maps or OSPF point-to-multipoint. But since you can't use this, you need on
each spoke site to override the next-hop address to the hub router (rather
than the spoke router) where needed. This is achieved by policy routing....
e.g.
R1-----R2
|
|
R3
Say R3 has a route: 192.168.10.0/24 reachable via R2
You need to policy route packets destined to 192.168.10.0/24 coming into R3
(and/or originating from R3). Specifically you need the following: 'If a
packet is destined for 192.168.10.0/24, set the next hop to R1'. As R3 and
reach R1 via inverse arp, the packet is sent successfully to R1 - R1 then
forwards to R2.
Remember, policy routing is applied to INCOMING traffic on an interface....
e.g.
R3:
int e0
ip policy route TEST
route-map TEST permit 10
match ip address prefix-list SPOKE
set ip next-hop R1
route-map TEST permit 20
ip prefix-list SPOKE permit 192.168.10.0/24
ip local policy route TEST ! This applies policy routing to packets
originating from router itself
Regards,
Justin Menga CCIE #6640 MCSE+I CCSE
WAN Specialist
Computerland New Zealand
PO Box 3631, Auckland
DDI: (+64) 9 360 4864 Mobile: (+64) 25 349 599
mailto: justin.menga@computerland.co.nz
-----Original Message-----
From: Patrick Bikar [mailto:pbikar@cisco.com]
Sent: Wednesday, 7 February 2001 10:31 p.m.
To: Ronnie Royston; ccielab@groupstudy.com
Subject: Re: Great Frame Relay Information Link
Thanks for the link Ronnie !
However, I cannot seem to find any info on the following problem :
On FR/OSPF, when you are not allowed to use "ip ospf netw" nor "frame-relay
map", I have seen that some of you mention a method involving
policy-routing,
together with "neighbor" statements.
Doyle does not talk about it, and I don't find any info/links/archives
speaking
about it . Can anyone please enlighten my poor soul ?
Thanks for any hints,
Patrick.
1st attempt : 15th March.
At 13:10 06/02/2001 -0600, Ronnie Royston wrote:
>Hi everyone. I thought most of you would be interested in this link:
>
>http://www.cisco.com/warp/public/125/12.html
>
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