bgp sending community string

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bgp sending community string

mottycruz
trying to send a community string to our neighbor here is my configuration:

# ISP peer 1 announcements only#
neighbor 19.25.16.13 {
         remote-as       7X32
         descr           "level1"
         announce all
         set community 7X32:100
        tcp md5sig password "passwd2"
}

here is how our neighbor see my router:

KRT in-kernel 19.16.16.0/22 -> {19.25.16.14}
Page 0 idx 0 Type 1 val a4e65a0
Nexthop: 19.25.16.14
     MED: 0
Localpref: 300
     AS path: [3XX2] 2XX1 2XX12XX12XX1I
     Communities: 3xx2:2900

  I want "localpref" to be much lower for them. They have configured the
"community string" on their side, however we're not sending that string,
I believe my syntax may be wrong.

any ideas?

Thanks,

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Re: bgp sending community string

Claudio Jeker
On Wed, May 13, 2015 at 10:36:09AM -0700, Motty Cruz wrote:

> trying to send a community string to our neighbor here is my configuration:
>
> # ISP peer 1 announcements only#
> neighbor 19.25.16.13 {
>          remote-as       7X32
>          descr           "level1"
>          announce all
>          set community 7X32:100
>         tcp md5sig password "passwd2"
> }
>
> here is how our neighbor see my router:
>
> KRT in-kernel 19.16.16.0/22 -> {19.25.16.14}
> Page 0 idx 0 Type 1 val a4e65a0
> Nexthop: 19.25.16.14
>      MED: 0
> Localpref: 300
>      AS path: [3XX2] 2XX1 2XX12XX12XX1I
>      Communities: 3xx2:2900
>
>   I want "localpref" to be much lower for them. They have configured the
> "community string" on their side, however we're not sending that string,
> I believe my syntax may be wrong.
>
> any ideas?

From bgpd.conf man page:
     set attribute ...
             Set the AS path attributes to some default per neighbor or group
             block:

                   set localpref 300

             See also the ATTRIBUTE SET section.  Set parameters are applied
             to the received prefixes; the only exceptions are prepend-self,
             nexthop no-modify and nexthop self.  These sets are rewritten
             into filter rules and can be viewed with ``bgpd -nv''.

So yes, expected behaviour your config is tagging the incoming prefixes
with the community and not the sent one.

Either set the community on the network statement that defines what you
announce or do it as a filter:

match to 19.25.16.13 set community X:Y

--
:wq Claudio