[c-nsp] Running OSPF on PE-to-CE

Enno Rey erey at ernw.de
Sun Oct 16 04:31:10 EDT 2011


Hi,

this one might be helpful

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ospfshmk.html

thanks

Enno

-- 
Enno Rey

ERNW GmbH - Breslauer Str. 28 - 69124 Heidelberg - www.ernw.de
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On Sun, Oct 16, 2011 at 04:02:38PM +0800, ar wrote:
> ??? 
> 
> Can somebody tell me why this route is being prefered?
> 
> I have 2 customer edge router. one on each site. The are linked together running ospf for intra-area routes. Multihomed to the MPLS VPN service provider using OSPF also as PE-to-CE? routing protocol. Routes are redistributed so they are both E2 routes.
> 
> Here's the outpu from one of my CE. I am trying to check show ip route the loopback address of CE2 from CE1.
> 
> 
> Here's the route of CE-2's loopback via the MPLS/VPN
> 
> 
> CE1#sho ip route 10.30.30.30
> Routing entry for 10.30.30.30/32
> ? Known via "ospf 10", distance 110, metric 1
> ? Tag Complete, Path Length == 1, AS 10, , type extern 2, forward metric 1
> ? Last update from 172.16.2.1 on FastEthernet0/0, 00:01:47 ago
> ? Routing Descriptor Blocks:
> ? * 172.16.2.1, from 10.2.2.2, 00:01:47 ago, via FastEthernet0/0
> ????? Route metric is 1, traffic share count is 1
> ????? Route tag 3489660938
> 
> 
> Here's the CE-2's loopback via the Intra-area link. (elected as best path always)
> 
> CE1#sho ip route 10.30.30.30
> Routing entry for 10.30.30.30/32
> ? Known via "ospf 10", distance 110, metric 20, type extern 2, forward metric 1000
> ? Last update from 172.16.3.1 on FastEthernet1/0, 00:00:08 ago
> ? Routing Descriptor Blocks:
> ? * 172.16.3.1, from 10.30.30.30, 00:00:08 ago, via FastEthernet1/0
> ????? Route metric is 20, traffic share count is 1
> 
> 
> Loopback IP is just redistributed to OSPF so it should be an E2 route.
> 
> However based on the two routes above, the one via the intra-area link is always being prefered over the one via the MPLS network even if I adjust the redistribution metric. Both are E2 routes already. What's the difference between the two routes and why the other is being prefered always regardless of metric set?
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-- 
Enno Rey

ERNW GmbH - Breslauer Str. 28 - 69124 Heidelberg - www.ernw.de
Tel. +49 6221 480390 - Fax 6221 419008 - Cell +49 174 3082474
PGP FP 055F B3F3 FE9D 71DD C0D5  444E C611 033E 3296 1CC1

Handelsregister Mannheim: HRB 337135
Geschaeftsfuehrer: Enno Rey

=======================================================
Blog: www.insinuator.net || Conference: www.troopers.de
=======================================================


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