[j-nsp] Troubleshooting BGP

Stevanus stevanus at datacomm.co.id
Wed Oct 7 22:28:26 EDT 2009


Try to set advertise-inactive in bgp configuration setting

- Stevanus -

Jason Lixfeld wrote:
> If I'm reading this correctly, the router is preferring the OSPF route
> over the BGP route, which makes sense because OSPF has a lower
> administrative distance (is that a Juniper term too, or just a Cisco
> term?) than iBGP.  This shouldn't prevent the route from being
> announced to eBGP peers (at least it doesn't in Cisco land, but maybe
> there are differences in how J and C work in this regard which I'm
> missing) should it?
>
> user at router> show route 69.57.14.0 detail
>
> inet.0: 296972 destinations, 664182 routes (296971 active, 0 holddown,
> 1 hidden)
> 69.57.14.0/24 (2 entries, 1 announced)
>          *OSPF   Preference: 150
>                  Next hop type: Router, Next hop index: 530
>                  Next-hop reference count: 1262
>                  Next hop: 72.15.49.21 via ge-2/0/1.0, selected
>                  State: <Active Int Ext>
>                  Local AS: 21949
>                  Age: 1:11:22   Metric: 2020    Tag: 0
>                  Task: OSPFv2
>                  Announcement bits (2): 0-KRT 5-Resolve tree 1
>                  AS path: I
>           BGP    Preference: 170/-791
>                  Next hop type: Indirect
>                  Next-hop reference count: 1
>                  Source: 72.15.48.2
>                  Next hop type: Router, Next hop index: 530
>                  Next hop: 72.15.49.21 via ge-2/0/1.0, selected
>                  Protocol next hop: 206.223.182.67
>                  Indirect next hop: 155101d4 1048579
>                  State: <Int Ext>
>                  Inactive reason: Route Preference
>                  Local AS: 21949 Peer AS: 21949
>                  Age: 1:11:27   Metric: 0       Metric2: 2020
>                  Task: BGP_21949.72.15.48.2+179
>                  AS path: I (Originator) Cluster list:  66.207.194.20
>                  AS path:  Originator ID: 72.15.48.6
>                  Communities: 21949:70 21949:790
>                  Localpref: 790
>                  Router ID: 66.207.194.20
>
> user at router>
>
> On 2009-10-07, at 7:42 PM, Stefan Fouant wrote:
>
>   
>> You may have received the route via your iBGP peer, but is it active?
>> Do a 'show route x.x.x.x detail' to see if that particular route is
>> active in the routing table and post your results here...
>>
>>
>>
>> On 10/7/09, Jason Lixfeld <jason at lixfeld.ca> wrote:
>>     
>>> I'm pretty new to JunOS and I'm running up against an issue that I'm
>>> not sure how to troubleshoot or debug.
>>>
>>> I have an iBGP prefix that is being learned by my M120/9.1R1.8 box,
>>> but it's not being announced to eBGP peers:
>>>
>>> user at router> show route advertising-protocol bgp 38.104.158.173 |
>>> match 69.57
>>>
>>> user at router>
>>>
>>> I see the prefix has been received from the iBGP router:
>>>
>>> user at router> show route receive-protocol bgp 72.15.48.2 extensive
>>> 69.57.14.0/24
>>>
>>> inet.0: 296881 destinations, 664001 routes (296880 active, 0
>>> holddown,
>>> 1 hidden)
>>>   69.57.14.0/24 (2 entries, 1 announced)
>>>      Nexthop: 72.15.48.6
>>>      MED: 0
>>>      Localpref: 790
>>>      AS path: I (Originator) Cluster list:  66.207.194.20
>>>      AS path:  Originator ID: 72.15.48.6
>>>      Communities: 21949:70 21949:790
>>>
>>> user at router>
>>>
>>> Looking at the configuration for this particular eBGP peer, it's
>>> configured to announce prefixes tagged with one of the communities
>>> attached to this route, 21949:70.  I've also verified that there are
>>> other prefixes with the same communities as above being announced to
>>> this eBGP peer without incident.
>>>
>>> user at router> show configuration protocols bgp group paidpeers
>>> type external;
>>> mtu-discovery;
>>> import PP-NA-TOR-FRONT-GENERIC-IN;
>>> export PP-GENERIC-OUT;
>>> neighbor 38.104.158.173 {
>>>     family inet {
>>>         unicast;
>>>     }
>>>     peer-as 174;
>>> }
>>>
>>> user at router> show configuration policy-options policy-statement PP-
>>> GENERIC-OUT
>>> term transit-routes {
>>>     from community TRANSIT;
>>>     then reject;
>>> }
>>> term peering-routes {
>>>     from community PEERING;
>>>     then reject;
>>> }
>>> term paidpeering-routes {
>>>     from community PAIDPEERING;
>>>     then reject;
>>> }
>>> term local-routes {
>>>     from community LOCAL;
>>>     then {
>>>         community delete all;
>>>         accept;
>>>     }
>>> }
>>> term customer-routes {
>>>     from community CUSTOMER;
>>>     then {
>>>         community delete all;
>>>         accept;
>>>     }
>>> }
>>> term backbone-static {
>>>     from {
>>>         protocol static;
>>>         route-filter 72.15.48.0/20 exact;
>>>     }
>>>     then accept;
>>> }
>>> term default {
>>>     then reject;
>>> }
>>>
>>> user at router> show configuration policy-options community LOCAL
>>> members 21949:70;
>>>
>>> Just to be sure there aren't any typos in the community lists, there
>>> is only one that has 21949:70 as a member:
>>>
>>> user at router> show configuration policy-options | match 21949:70
>>> community LOCAL members 21949:70;
>>>
>>> user at router>
>>>
>>> I'm at a loss to understand why or how this prefix is any different
>>> than any of the others that match the same community string.  I've
>>> tried to monitor bgp traceoptions flag update and while I see updates
>>> coming through, I don't see anything for this specific prefix even if
>>> I withdraw it from iBGP (I'd expect to see an update because the
>>> prefix is certainly withdrawn from the BGP table on the router as I
>>> remove it from BGP on the originating router).
>>>
>>> Anyone have any ideas on either the issue itself or how I can get
>>> some
>>> more debugging/troubleshooting info out of the box?
>>> _______________________________________________
>>> juniper-nsp mailing list juniper-nsp at puck.nether.net
>>> https://puck.nether.net/mailman/listinfo/juniper-nsp
>>>
>>>       
>> --
>> Stefan Fouant
>>
>>     
>
> _______________________________________________
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> .
>
>   


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