From: Tom Lijnse (Tom.Lijnse@globalknowledge.nl)
Date: Tue Feb 24 2004 - 11:36:45 GMT-3
Hi Mike,
if you're willing to use a 12.2T or 12.3 main release IOS you could have a look at the Enhanced Object tracking feature:
This would basically allow your Router A to become the HSRP master if the link to the MPLS cloud on Router D fails. (You can have Router B track reachability of the subnet that belongs to the MPLS link on Router D).
I haven't personally used this on any real network, so obviously it would require some testing.
Alternatively you could implement policy based routing on Router D to route packets back to Router B if the link to the MPLS cloud is down. Because there's no PBR on the interface of Router B that the packets are coming back on, they will be routed normally. (And if I understand your scenario correctly that would mean sending them on to Router A).
I think this is an ugly solution though, since all the voice traffic will be bounced between B and D. I think the object tracking could provide you with a more elegant solution.
Just my $ 0.02
Regards,
Tom Lijnse
CCIE #11031
Global Knowledge Netherlands
-----Original Message-----
From: Nordhoff, Michael G. (US - Hermitage)
[mailto:mnordhoff@deloitte.com]
Sent: Tuesday, February 24, 2004 3:13 PM
To: ccielab@groupstudy.com
Subject: Policy-based Routing (Failover)
Any ideas on handling the following scenario that incorporates 4 routers
and policy-based routing (PBR)?
Rtr A --- Rtr C --- MPLS Carrier 2
|
Rtr B --- Rtr D --- MPLS Carrier 1
Router A and Router B are directly connected. Router B is the primary
router in an HSRP group with Router A. Router A is connected to Router
C which connects to MPLS carrier 2. Router B is connected to Router D
which connects to MPLS carrier 1. PBR is implemented on the ingress
port of Router B such that all voice traffic is sent to Router D as long
as it is up and to Router A if Router D is down. All other traffic is
sent to Router A as long as it is up and to Router D if Router A is
down. The problem is that from Router B my PBR configuration cannot
detect an MPLS link failure on Router D and automatically redirect all
traffic to Router A. I've implemented PBR because I need to route
packets based on more than just destination network. I'm not
necessarily locked-in to using PBR if there is a better way to
accomplish this. Any thoughts?
Mike Nordhoff - CCIE #12849
WAN Engineer
Deloitte Services LP
Main: +1 615-882-7600
Direct: +1 615-882-7741
Pager: +1 888-490-3968
Mobile: +1 615-403-7869
mnordhoff@deloitte.com
www.deloitte.com
4022 Sells Drive
Hermitage, TN 37076
United States
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