Cnange next-hop

[Ondrej Zajicek]

On Fri, Apr 04, 2014 at 06:19:28PM +0300, Alexander Shikov wrote:
> Hi,
> 
> continuing the implemetation of blackhole in our IXP, I've faced with problem of 
> changing next-hop for the route.
> 
> Construction looks like
> 
> if (net.len = 32 && bgp_community ~ [ (31210,*) ] && bgp_community ~ [ (0,666) ] ) then {
> 	gw = 193.25.181.253;
> 	return true;
> }
> 
> results in :
> 
> bird> show route for 95.67.13.2/32 all 
> 95.67.13.2/32      via 193.25.181.253 on bge0 [COSMONOVA2 2014-04-04 17:59:19 from 193.25.180.133] * (50) [AS34867i]
>         Type: BGP unicast univ
>         BGP.origin: IGP
>         BGP.as_path: 34867
>         BGP.next_hop: 193.25.180.133
>         BGP.local_pref: 100
>         BGP.community: (0,666) (31210,31210)
> 
> 
> And when this route is announced to other peer, next-hop remains unchanged:
> 
> Peerings.inet.0: 16708 destinations, 50556 routes (16627 active, 0 holddown, 88 hidden)
> + = Active Route, - = Last Active, * = Both
> 
> 95.67.13.2/32      *[BGP/170] 00:12:14, localpref 100, from 193.25.180.255
>                       AS path: 34867 I
>                     > to 193.25.180.133 via xe-1/0/0.777
> 
> As far as I understand from User's Guide, gw is an read-write attribute,
> so why it didn't change next-hop?

Because gw and bgp_next_hop are related but separate attributes. You
have to change bgp_next_hop.

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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