[c-nsp] BGP not advertising supernet to RR's

Mattias Gyllenvarg mattias at gyllenvarg.se
Tue Sep 26 02:32:36 EDT 2017


You can test the hits in the route-map with "sh ip bgp route-map G----_RANGES"
and see if it hits correctly.

If the redist statements are new then they will take time to be
implemented, 20min I think for a full BGP rerun. If you are in a hurry,
remove and re add the route.

Do you receive this route via BGP aswell? Perhaps this is not the best
route as BGP sees it.

tis 26 sep. 2017 kl 08:10 skrev CiscoNSP List <CiscoNSP_list at hotmail.com>:

> Hi Everyone,
>
>
> Have a problem with supernet being advertised from an ASR1006 to our RR's
> - Prefix is in the routing table, and in bgp, but the router is only
> advertising smaller prefixes to the RR's (/30,/29, 28 etc)...I
>
> dont *think* its due to the PL (As it should be allowing anything less
> that /32...which it appears to be doing as /30,/29 etc are being
> advertised?)
>
>
> Appreciate any assistance.
>
>
> ** Ah - Update, just noticed as I was about to hit send that the supernet
> is not being tagged with any community.....smaller prefixes are though? So
> route-map is tagging "some" prefixes within the
>
> supernet?
>
>
> router bgp 1***6
>  address-family ipv4
>   redistribute connected route-map G----_RANGES
>   redistribute static route-map G----_RANGES
>
>
> neighbor xxx.xxx.76.204 route-map TO_ME1_RR out
>
>
> route-map TO_ME1_RR permit 10
>  match community CL_G----_RANGES
> route-map TO_ME1_RR permit 20
>  match community CL_G----_CUST_BGP_RANGES
> route-map TO_ME1_RR permit 30
>  match community CL_DEFAULT_ROUTE
>
>
> ip community-list standard CL_G----_RANGES permit 1***6:1301
> ip community-list standard CL_G----_RANGES permit 1***6:1302
>
>
> route-map G----_RANGES permit 10
>  match ip address prefix-list PL_G----_PREFIXES
>  set community 1***6:1000 1***6:1301 1***6:11000
> route-map G----_RANGES permit 20
>  match ip address prefix-list PL_N***S_PREFIXES
>  set community 1***6:1400
>
>
> ip prefix-list PL_G----_PREFIXES description G---- _PREFIXES
> ip prefix-list PL_G----_PREFIXES seq 5 permit xxx.xxx.xxx.xxx.0/20 le 32
> ip prefix-list PL_G----_PREFIXES seq 10 permit yyy.yyy.yyy.yyy/21 le 32
>
>
>
> #sh ip prefix-list PL_G----_PREFIXES seq 5
>    seq 5 permit xxx.xxx.xxx.xxx.0/20 le 32 (hit count: 4833, refcount: 1)
>
>
> #sh ip route xxx.xxx.xxx.xxx.0 255.255.240.0
> Routing entry for xxx.xxx.xxx.xxx.0/20, supernet
>   Known via "static", distance 1, metric 0 (connected)
>   Redistributing via bgp 1***6, ospf 100
>   Advertised by bgp 1***6 route-map G----_RANGES
>   Routing Descriptor Blocks:
>   * directly connected, via Null0
>       Route metric is 0, traffic share count is 1
>
>
> #sh ip bgp xxx.xxx.xxx.xxx.0 255.255.240.0
> BGP routing table entry for xxx.xxx.xxx.xxx.0/20, version 311740657
> Paths: (1 available, best #1, table default)
>   Advertised to update-groups:
>      544        552        555        591
>   Refresh Epoch 1
>   Local
>     0.0.0.0 from 0.0.0.0 (xxx.xxx.76.253)
>       Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced,
> local, best
>       rx pathid: 0, tx pathid: 0x0
>
>
> #sh ip bgp neighbors xxx.xxx.76.204 advertised-routes
>
>  *>  xxx.xxx.xxx.xxx.32/30 0.0.0.0                  0         32768 ?
>  *>  xxx.xxx.xxx.xxx.40/30 0.0.0.0                  0         32768 ?
>  *>  xxx.xxx.xxx.xxx.72/29 xxx.xxx.xxx.xxx.90            0         32768 ?
>  *>  xxx.xxx.xxx.xxx.88/30 0.0.0.0                  0         32768 ?
>  *>  xxx.xxx.xxx.xxx.100/30
>                        0.0.0.0                  0         32768 ?
>      Network          Next Hop            Metric LocPrf Weight Path
>  *>  xxx.xxx.xxx.xxx.112/28
>                        xxx.xxx.78.230           0         32768 ?
>  *>  xxx.xxx.xxx.xxx.136/30
>                        xxx.xxx.78.230           0         32768 ?
>  *>  xxx.xxx.xxx.xxx.164/30
>                        xxx.xxx.xxx.xxx.102           0         32768 ?
>
>
> Thanks
>
>
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>
-- 
Mvh
Mattias Gyllenvarg


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