neighbor ip-address as-override

Answered Question
Apr 21st, 2010
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Hi All,


I am not able to configure the neighbor ip-address as-override command on my cisco 2821 router.


My router ios - c2800nm-advsecurityk9-mz.124-15.T9.bin.


What should I do for that command to work on my router?

Correct Answer by Jon Marshall about 7 years 1 month ago

NSG_POLARIS wrote:


Jon,

Sorry.


I am not able to add "neighbor ip-address as-override" command under bgp configuration.


Just to clarify, the as-override feature is available for MPLS configurations and is configured under the "address-family ..." subsection under the router bgp . So you can't configure it directly under the "router bgp " eg.


7200(config)# router bgp 65100

7200(config-router)# neighbor 192.168.7.1  <--- as-override cannot be configured here


7200(config-router)# address-family ipv4 vrf TEST

7200(config-router-af)# neighbir 192.168.7.1 as-override


Apologies if you already knew this.


Jon

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Jon Marshall Wed, 04/21/2010 - 08:31
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NSG_POLARIS wrote:


Hi All,


I am not able to configure the neighbor ip-address allowas-in [number] command on my cisco 2821 router.


My router ios - c2800nm-advsecurityk9-mz.124-15.T9.bin.


What should I do for that command to work on my router?


That's weird, you should be able to. What error message do you get when you try to configure it ?


Under the router bgp when you type "neighbor x.x.x.x ?" what do you get as options ?


Jon

NSG_POLARIS Wed, 04/21/2010 - 09:49
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Jon,

Sorry.


I am not able to add "neighbor ip-address as-override" command under bgp configuration.

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Jon Marshall Wed, 04/21/2010 - 10:16
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NSG_POLARIS wrote:


Jon,

Sorry.


I am not able to add "neighbor ip-address as-override" command under bgp configuration.


Just to clarify, the as-override feature is available for MPLS configurations and is configured under the "address-family ..." subsection under the router bgp . So you can't configure it directly under the "router bgp " eg.


7200(config)# router bgp 65100

7200(config-router)# neighbor 192.168.7.1  <--- as-override cannot be configured here


7200(config-router)# address-family ipv4 vrf TEST

7200(config-router-af)# neighbir 192.168.7.1 as-override


Apologies if you already knew this.


Jon

NSG_POLARIS Wed, 04/21/2010 - 10:47
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Hi Jon,


Thanks for your valuable reply.I got clarified.


What is the difference between the MPLS and BGP configuration. Do share if you have any document.

Jon Marshall Wed, 04/21/2010 - 11:13
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MPLS uses BGP or more specifically MP-BGP between PE routers to pass VRF/VPN information.


What exactly are you trying to do ?


Jon

NSG_POLARIS Wed, 04/21/2010 - 18:44
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Jon,


I am facing network issue with one of my MPLS service provider.


The specific network AS travell path is repeating.


In the show ip bgp output we found that the AS is repeating

Ex

CE-ROUTER#show ip bgp 10.180.8.64
BGP routing table entry for 10.180.8.64/26, version 46224
    192.168.255.101 (metric 12) from 192.168.255.101 (192.168.255.101)
      Origin incomplete, localpref 120, valid, external, best

    1 6755 4655 32496 64547 65247

remote-as for my CE is 6755.

As this AS 6755is repeating I asked my service provider to add the command allowas-in in PE router.

Instead my service provider asked me to add the command as-override command on my CE router.But my router is running BGP and there is no MPLS configuration.

If I have some document to understand the difference between MPLS and BGP configuration I can clarify the same to my Service provider.

Rgds,

Gopi

KARUPPUCHAMY MA... Wed, 04/21/2010 - 20:23
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Hi,


No use of adding "neighbor   as-override"  in CE side router.Moreover AS 6755 is not repeating as per your "show ip bgp 10.180.8.64"


can you post your setup please..


whenever you advertise network into MPLS cloud via your  Site A CE BGP, it will advertise into the MPLS cloud with your AS number, then  the same bgp update has to send your another site Site BCE router.Now the Site B CE router won't accept the routes which is advertising from site A because of the same AS number.


In this scenario the ISP will replace your AS with their AS by the use of "neighbor   as-override" . or you can add neighbor allowas-in in your CE side router.


Thanks

Karuppu

NSG_POLARIS Wed, 04/21/2010 - 22:09
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Hi,


Its correct.No use of adding "neighbor   as-override"  in CE side router.Moreover this command is the MPLS command and can not configure on my CE as I am using BGP.

cpubob Wed, 04/21/2010 - 12:26
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Upgrade to the SPservices or higher feature set.


GL


-Rob

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