Re: OT - BGP command output interpretation

From: Marko Milivojevic <markom_at_ipexpert.com>
Date: Mon, 15 Mar 2010 20:31:46 +0000

You are very welcome.

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
Mailto: markom_at_ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Web: http://www.ipexpert.com/
On Mon, Mar 15, 2010 at 20:17,  <Charles.Henson_at_regions.com> wrote:
> That is what I needed to hear. So the commands make sense. I am filtering
> it (by now allowing it specifically) in a prefix list I have applied
> inbound to my BGP. I have found the problem.
>
> THANKS MARKO!
>
> Charles Henson
>
>
>
>
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> B |Charles.Henson_at_regions.com B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B |
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> B |03/15/2010 03:12 PM B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  |
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> B |Re: OT - BGP command output interpretation B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B  B |
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>
> Hi,
>
> The command "sh ip bgp nei x.x.x.x received-routes" will show you
> prefixes BEFORE they pass through your inbound filters. Do you see
> prefix with "sh ip bgp nei x.x.x.x routes". If not, you need to look
> at your inbound filtering.
>
> --
> Marko Milivojevic - CCIE #18427
> Senior Technical Instructor - IPexpert
>
> Mailto: markom_at_ipexpert.com
> Telephone: +1.810.326.1444
> Fax: +1.810.454.0130
> Web: http://www.ipexpert.com/
>
> On Mon, Mar 15, 2010 at 19:59, B <Charles.Henson_at_regions.com> wrote:
>> Well... kinda OT..... So I'm troubleshooting some BGP and putting my
> study
>> skills to good work and having a bit of an issue.
>>
>> PROBLEM:
>> B B B B B B B Router has no 0/0 route. Router is supposed to get 0/0 from
> BGP peer.
>> Then OSPF on same router (via default information originate) will feed it
>> on to WAN. No "always" applied to OSPF Default information originate
>> statement.
>>
>> x.x.x.y is my upstream provider. z.z.z.z is my IBGP peer for redundancy.
> I
>> see that it is not feeding me any prefixes. Normally I have 1 prefix (the
>> 0/0 route) and that is all I need. So the way I'm reading the below
>> statement, it looks to me like I'm not being fed any route(s). So if that
>> is the case than the below output looks logical and I need to go yell at
> my
>> carrier.
>>
> ###############################################################################################
>
>> ROUTER-1#show ip bgp summ
>> BGP router identifier x.x.x.x, local AS number 9999
>> BGP table version is 38, main routing table version 38
>> 5 network entries using 585 bytes of memory
>> 9 path entries using 468 bytes of memory
>> 6/2 BGP path/bestpath attribute entries using 744 bytes of memory
>> 1 BGP AS-PATH entries using 24 bytes of memory
>> 0 BGP route-map cache entries using 0 bytes of memory
>> 0 BGP filter-list cache entries using 0 bytes of memory
>> BGP using 1821 total bytes of memory
>> 1 received paths for inbound soft reconfiguration
>> BGP activity 9/4 prefixes, 42/33 paths, scan interval 60 secs
>>
>> Neighbor B B B B B B B V B B B AS MsgRcvd MsgSent B B TblVer B InQ OutQ
> Up/Down
>> State/PfxRcd
>> x.x.x.y B B B 4 B 1234 B 137818 B 137857 B B B B B B 38 B B B 0 B B B 0
> 01:52:26 B B B B B B B 0
>> z.z.z.z B B B 4 9999 B 137867 B 137858 B B B B B B 38 B B B 0 B B B 0 00:01:14
> B B B B B B B 4
>>
>> ROUTER-1#show ip bgp
>> BGP table version is 38, local router ID is x.x.x.x
>> Status codes: s suppressed, d damped, h history, * valid, > best, i -
>> internal,
>> B B B B B B B B B B B B B r RIB-failure, S Stale
>> Origin codes: i - IGP, e - EGP, ? - incomplete
>>
>> [NO 0/0 ROUTE. NOTHING TO SEE HERE. MOVE ALONG]
>> B B Network B B B B B B B B B Next Hop B B B B B B B B B B B Metric LocPrf Weight
> Path
>>
>>
>>
> ###############################################################################################
>
>>
>> BUT WAIT. WHAT IS THIS?
>>
>> If I hit up my specific neighbor for received routes then BGP reports
> that
>> it has a 0/0 route from his peer. It's total prefix count is 1. Met and
>> local pref 0. That all looks good. The route is valid. But it is not
>> flagged as "best".
>>
> ################################################################################################
>
>> ROUTER-1#show ip bgp neighbors B B x.x.x.y received-routes
>> BGP table version is 38, local router ID is x.x.x.x
>> Status codes: s suppressed, d damped, h history, * valid, > best, i -
>> internal,
>> B B B B B B B B B B B B B r RIB-failure, S Stale
>> Origin codes: i - IGP, e - EGP, ? - incomplete
>>
>> B B Network B B B B B B B B B Next Hop B B B B B B B B B B B Metric LocPrf Weight
> Path
>> * B 0.0.0.0 B B B B B B B B B x.x.x.y B B B B B B B B B B B B 0 B B B B B B B B B B B B 0
> 1234 i
>>
>> Total number of prefixes 1
>>
> ################################################################################################
>
>>
>> So my BGP summary commands sho zero prefixes being received by me. But my
>> neighbor specific command shows the 0/0 being received and the prefixes
>> totalling 1. This is my problem. The 0/0 route appears there but it's not
>> getting passed to the RIB. Now I have no other static or dynamic 0/0
> routes
>> or anything else with a lower AD. I have no RIB failures.
>>
>> 1. Am I understanding the command output above correctly? I believe that
> I
>> am based on CCO and checking with my local Cisco guy. He's nosing around
> as
>> well but feels that something is amiss here.
>>
>> 2. If I (we) are interpreting the command output above correctly, then
> does
>> the conflict between the commands make sense? Any thoughts?
>>
>> I have bounced the router and still have the same issue. To bring things
> up
>> I have added a static to to see if that would work. It did. So the next
> hop
>> is valid. Anyone?
>>
>> [IP addressing and ASNs have been changed to protect the innocent. Yes, I
>> am aware that some creative googling will reveal all anyway.]
>>
>>
>> Charles Henson
>>
>>
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>>
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Received on Mon Mar 15 2010 - 20:31:46 ART

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