Partial routing updates with MPLS via BGP

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Feb 21st, 2008
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I am having an issue with only receiving a partial routing table at a new site connected via Verizon's MPLS service.


The routing protocol used for PE-CE is BGP. The routers involved are all 2821 running the same version of software - v12.4(11).


The new site receive route information for most of the existing sites, but does not get route info for a few specific sites. The BGP routing configuration is the same at all site except for the site specific information.


Basically, Site D is a new site. Site D receives routing info. for sites B and C, but not A.


Sites A receives route info for sites B and C, but not D.


A trace route from A to D, dies after the PE device at site D. A trace route from D to A fails imediately.



A sample of the BGP routing config is below:

router bgp 1

no synchronization

bgp log-neighbor-changes

redistribute eigrp ### metric 20

neighbor x.x.x.x remote-as #####

no auto-summary



I'm not sure if the issue is with our routing, or if Verizon's PE is not passing all the routing updates.


Anyone has any sugestions?


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Joseph W. Doherty Thu, 02/21/2008 - 17:59
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For the new site D, use the show bgp neighbor command to see the routes being received from the provider peer and to confirm what site D is sending to the provider (you didn't mention whether sites B and C see D).

mike.rootvik Thu, 02/21/2008 - 21:20
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Sites B and C are receive route info for both Site A and D.


Sh BGP on A show no information for site D, and Sh BGP on site D show no information for A.


Both A and D show BGP entries for sites B and C.

Joseph W. Doherty Fri, 02/22/2008 - 05:28
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Assuming there's no inbound BGP filters, route maps, etc. on either site A and D, then if you haven't already, you could try a bgp clear inbound at both sites A and D. If routes still not there, might be time to contact MPLS vendor.

mike.rootvik Fri, 02/22/2008 - 08:18
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Unfortunately, the bgp clear did not work. so I'll be calling the vendor.


thanks for the hrlp.

Joseph W. Doherty Fri, 02/22/2008 - 08:36
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If possible, let us know about problem resolution.

Mohamed Sobair Sun, 02/24/2008 - 11:10
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Hi,


1st, if you are running bgp as a CE-PE routing protocol, the above shouldnt be the config sample. why are you redistributing Eigrp?


Could you check you BGP routing table at Site-A & D.


The Symptoms appears as there is no route back from Site-D to A.


This could be due to a lot of problems at the service provider, whether the Networks at Site-D are not advertised through MP-BGP or it could be a route-target issue at the service provider.


Pls let us know how you routing table look like at both sites.


HTH

Mohamed

royalblues Mon, 02/25/2008 - 01:23
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Can you try configuring the following under the BGP session at D


router bgp 1

neighbor x.x.x.x allow-as in


Narayan

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