From: Brian McGahan (brian@cyscoexpert.com)
Date: Tue Feb 18 2003 - 19:44:36 GMT-3
Syv,
The two most common reasons for a route not being best in the
BGP table are:
1. you don't have reachability to the next-hop address
2. the synchronization rule is not met.
Ensure that C has a route to 10.108.44.44. If not, you cannot
consider the route to be best.
The synchronization rule states that for all iBGP learned
prefixes, you must have a matching IGP route in order to consider it
best. In addition to this, if the IGP used to synchronize is OSPF, the
router-id of the BGP neighbor you are learning the prefix from and the
router-id of the originator into the OSPF domain must match. If all
routers in the transit path are running BGP, you could also just turn
synch off with the BGP command 'no synchronization'.
For more info on the BGP decision process:
http://www.cisco.com/en/US/tech/tk648/tk365/technologies_tech_note09186a
0080094431.shtml
HTH
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Toll Free: 866.CyscoXP
Fax: 847.674.2625
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Syv Ritch
> Sent: Tuesday, February 18, 2003 3:03 PM
> To: ccielab@groupstudy.com
> Subject: BGP & Route reflectors
>
> Hi,
>
> A [eBGP] --> B [RR client] --> C [Route Reflector] --> D [RR client]
>
> A is connected to the client and not to the route reflector.
> How do I propagate the route 10.108.144.0 from A:
>
> Router B:
>
> TS-2512#b
> BGP table version is 3, local router ID is 99.99.99.99
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> * i10.108.122.0/24 10.108.22.22 0 100 0 65110 i
> * i10.108.133.0/24 10.108.33.33 0 100 0 i
> *> 10.108.144.0/24 10.108.44.44 0 0 65244 i
> * i10.108.155.0/24 10.108.22.22 100 0 65110 i
> * i10.108.166.0/24 10.108.22.22 100 0 65110 i
> *> 10.108.199.0/24 0.0.0.0 0 32768 i
>
> Router C:
>
> c1720#b
> BGP table version is 5, local router ID is 33.33.33.33
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 10.108.122.0/24 10.108.22.22 0 0 65110 i
> *> 10.108.133.0/24 0.0.0.0 0 32768 i
> * i10.108.144.0/24 10.108.44.44 0 100 0 65244 i
> *> 10.108.155.0/24 10.108.22.22 0 65110 i
> *> 10.108.166.0/24 10.108.22.22 0 65110 i
> * i10.108.177.0/24 10.108.77.77 0 100 0 i
> * i10.108.199.0/24 10.108.99.99 0 100 0 i
>
> 10.108.144.0 is i and not *>
>
> Router D:
>
> c1602r#b
> BGP table version is 2, local router ID is 77.77.77.77
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> * i10.108.122.0/24 10.108.22.22 0 100 0 65110 i
> * i10.108.133.0/24 10.108.33.33 0 100 0 i
> * i10.108.155.0/24 10.108.22.22 100 0 65110 i
> * i10.108.166.0/24 10.108.22.22 100 0 65110 i
> *> 10.108.177.0/24 0.0.0.0 0 32768 i
>
> No 10.108.144.0
>
> --
> Thanks
> syv@911networks.com
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