Cisco's connected->bgp redistribution

Vijay Gill vijay at umbc.edu
Fri Jul 13 21:59:17 UTC 2001


On Fri, 13 Jul 2001, Bill Woodcock wrote:

>
>     > 	Can anyone shed some light on why cisco ignores "ip classless" when
>     > redistributing classless connected routes into bgp, making things such as
>     > /30 into /24s?
>
> Because you forgot to append the "subnets" keyword to your redist.

Subnets are not needed, chances are it is a failure of no auto-summary.
Autosummary is on by default.

router#show ip route x.y.106.122
Routing entry for x.y.106.120/30
  Known via "connected", distance 0, metric 0 (connected, via interface)
  Redistributing via bgp abcd
  Advertised by bgp abcd route-map connected-to-bgp
  Routing Descriptor Blocks:
  * directly connected, via Serial2/0/0:0
      Route metric is 0, traffic share count is 1

router#show int Serial2/0/0:0
Serial2/0/0:0 is up, line protocol is up
  Hardware is Multichannel T1
  Description: by the perception of illusion we experience reality
  Internet address is x.y.106.122/30

router bgp abcd
 no synchronization
 bgp log-neighbor-changes
 bgp dampening
 redistribute connected route-map connected-to-bgp
 redistribute static route-map static-to-bgp

 no auto-summary
!
ip classless


router#show ip bgp x.y.106.122
BGP routing table entry for x.y.106.120/30, version 11186014
Paths: (1 available, best #1)

etc

If you have no auto-summary turned on, then there might be a bug or more
probably, some sort of typo or mismatch (pilot error).

/vijay




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