BGP communities

[Bernd Naumann]

On 05.04.20 23:08, Fabiano D'Agostino wrote:
> Good evening,
> could someone explain me the meaning of these lines?
> 
> function bgp_out(int peeras)
> {
> if ! (source = RTS_BGP ) then return false;
> if peeras > 65535 then return true; ### communities do not support AS32
> if (0,peeras) ~ bgp_community then return false;
> if (myas,peeras) ~ bgp_community then return true;
> if (0, myas) ~ bgp_community then return false;
> return true;
> }
> 
> Thanks,
> 
> Fabiano
> 

Morning,

I can not cover the whole section but as a start...

* if the route does not come from BGP then false (routing table source?)
* if the remote AS Number is greater 65535 (16 Bit) then "just" return 
true (see AS 32 Bit Numbers, and the non-support of older 
devices/implementations)
* For the next 3 I'm not 100% sure how to read but I found 
https://bird-users.network.narkive.com/3uDbo6H9/any-ix-willing-to-share-their-config

```
0:XXXXX - Do not announce route to peer XXXXX
0:MyASN - Do not announce route to all peers
MyASN:XXXXX - Announce route to peer XXXXX only
MyASN:MyASN - Announce routes to all peers. This community is
automatically added to all routes that are not
tagged with any of MyASN:XXXXX communities.
```

Maybe this helps a little bit.

Bernd