[c-nsp] BGP blackhole community config

Rich Davies rich.davies at gmail.com
Sun Jun 19 21:06:04 EDT 2016

config term
ip bgp-community new-format
router bgp 100
 neighbor xx.xx.xx.xx remote-as 200 send-community

Try that and clear your BGP session.   Based on fact you have no "network"
statements to announce directly in BGP you are instead redistributing
static routes into BGP to be announced.   I believe you need to add the "ip
bgp-community new-format" to your global configuration and in addition tell
your neighbor statement to "send-community".

BGP community is an optional transitive attribute its only sent to external
ASN if you tell it to.

More on communities indicating they are (optional) transitive attributes:

On Sun, Jun 19, 2016 at 7:37 PM, Satish Patel <satish.txt at gmail.com> wrote:

> We have setup new BGP configuration with ISP and ISP has been told
> send community "64682:0" for blackholing. I am new in BGP.
> I was reading BGP community format is ASN:NN but my ISP ASN number
> isn't 64682 so i am assuming they gave me example (64682:0)
> This is what i configure in my router.
> router bgp 100
>  bgp log-neighbor-changes
>  redistribute static route-map RTBH
>  neighbor xx.xx.xx.xx remote-as 200
> route-map RTBH permit 10
>  match tag 666
>  set community <ISP_ASN>:666
> route-map RTBH permit 20
> I have send following null route but it didn't work :(
> ip route xx.x.x.xx Null0 tag 666
> what i am doing wrong? how do i use community to send blackhole route?
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