[c-nsp] Redistributed connected / static prefixes to upstream and set as-path prepend

CiscoNSP List CiscoNSP_list at hotmail.com
Fri Nov 24 11:07:52 EST 2017

Apologies - I did resolve this, but neglected to post to list....soft bgp reset, I saw no as prepends on carriers looking glass, same with hard reset (Hence I thought it was caused by origin (grasping at straws 😉 )) - I ended up shutting down the peering session, then activating it, and the AS Prepends miraculously showed up in carriers looking glass....fun 😊

From: Florin Florian <florin.florian at gmail.com>
Sent: Thursday, 2 November 2017 5:55 AM
To: CiscoNSP List
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Redistributed connected / static prefixes to upstream and set as-path prepend


You have to use the "ip bgp-community new-format" in order to see the community in the format.

You should try to configure "neighbor x.x.x.x send-community" for the community to be sent to the peer (upstream provider in this case).

Setting it in the route-map alone will not do it.


On Wed, Oct 25, 2017 at 1:24 AM, CiscoNSP List <CiscoNSP_list at hotmail.com<mailto:CiscoNSP_list at hotmail.com>> wrote:

We are redistributing our own prefixes via iBGP with redist connected + static with route-map :

router bgp AAAA
 address-family ipv4
  redistribute connected route-map OUR_RANGES
  redistribute static route-map OUR_RANGES

route-map OUR_RANGES permit 10
 match ip address prefix-list PL_OUR_RANGES
 set community AAAA:1000 AAAA:1301 AAAA:14000

ip prefix-list PL_OUR_RANGES seq 5 permit XXX.XXX.XXX.0/20 le 32

Which is working fine - but advertisement of the aggregate/supernet to our upstreams is not allowing prepending of as? (Have performed clear ip bgp nei_ip)

Is it because the prefixes are seen as Origin incomplete vs Origin IGP?

router bgp AAAA
 address-family ipv4

route-map UPSTREAM_A_OUT_OUT permit 30
 match ip address prefix-list PL_OUR_PREFIXES_OUT
 set as-path prepend AAAA

#sh ip bgp neighbors  WWW.WWW.WWW. advertised-routes
     Network          Next Hop            Metric LocPrf Weight Path
 *>i XXX.XXX.XXX.0/20  YYY.YYY.YYY.218           0    100      0 ?

#sh ip bgp route-map UPSTREAM_A_OUT_OUT
     Network          Next Hop            Metric LocPrf Weight Path
 * i XXX.XXX.XXX.0/20  YYY.YYY.YYY.217           0    100      0 ?
 *bi                  YYY.YYY.YYY.217           0    100      0 ?
 * i                  YYY.YYY.YYY.218           0    100      0 ?
 *>i                  YYY.YYY.YYY.218           0    100      0 ?

Thanks in advance.

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