02-28-2010 12:35 PM - edited 03-04-2019 07:39 AM
Hi, I need help on routing issue
HQ connects to DR site via 10mb fiber link
Branch office connects to HQ via service provider MPLS cloud
To overcome single point of failure for branch offices we got MPLS at DR site.
When HQ MPLS link goes down ; all branches cannot access HQ
Branch_router=====Service-Provider_router=====HQ_MPLS_RTR--------BackBone_RTR
Branch_router=====Service-Provider_router=====DR_MPLS_RTR--------BackBone_RTR
HQ_BackBone_RTR---------------------------DR_BackBone_RTR
Routing protocol on LAN : OSPF
Routing protocol for MPLS : BGP
On DR MPLS_RTR I get all routes for branches but these routes are not forwarded to DR Backbone_RTR,
there is already mutual redistribution, can you experts help on this.
How to manage getting updates from two different source to same destination on Backbone_RTRs
configuration attached
thanks to all
02-28-2010 12:49 PM
Hi,
A quick look of your configuration, you are missing
1, keyword "subnets" when redistributing bgp into ospf.
2, keyword " match external" when redistributing ospf into bgp. By default only ospf internal route will be redistributed into BGP, if you want the ospf external routes get redistributed into BGP, you need to use match keyword.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800943c5.shtml
Also be aware when doing mutual redistribution, loop might occur.
HTH,
Lei TIan
02-28-2010 01:01 PM
thanks for replying
mutual redistribution is needed, how to overcome the loop concern.
02-28-2010 01:13 PM
Hi,
There are multiple ways to prevent loop when mutual redistribution is required; it might vary on each network. You need to look closely on the network and how the route flows.
In general, you can tag the routes when it redistribute from protocol 1 into protocol 2, and block those routes when redistribute from protocol 2 back to protocol 1. Same rule for redistributing protocol 2 into protocol 1.
You can find a good reference for redistribution
http://blog.internetworkexpert.com/2008/02/09/understanding-redistribution-part-i/
HTH,
Lei Tian
02-28-2010 09:47 PM
Thanks link is very useful
Can you help with cisco link with config examples and more complex scenarios.
IE (part II ) on redistribution is kool as well
thanks again
03-01-2010 05:50 AM
Hi,
I couldn't find a good reference on cisco.com, but you can consider a cisco press book "Optimal Routing Design" by Russ White.
HTH,
Lei Tian
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