Pipe collision detected when sending to table

[Ondrej Zajicek]

On Wed, Sep 22, 2010 at 01:06:53PM +0200, Stefan Jakob wrote:
> Dear List and Bird-Pros,
> 
> Today we changed our RS config to an additional "Collector" table. We
> see this "<ERR>" in our logs:
> 
> 2010-09-22 11:02:02 <ERR> Pipe collision detected when sending
> W.X.Y.Z/24 to table Collector
> 
> This is seen for a couple of prefixes.
> 
> Any hint what we might have messed up?

This problem may happen if one route (from one protocol) arrives to one
routing table via two (or more) different pipes. The original idea is
that the graph of routes and pipes is a tree, but it should work even
if it is a tree for each route after applying filters.

I checked the config file and it seems that there are several ways for
one route to get to the collector table:

BGP1 - TABLE1 - COLLECTOR
BGP1 - TABLE1 - MASTER - TABLE2 - COLLECTOR
BGP1 - TABLE1 - MASTER - TABLE3 - COLLECTOR
...

The proper way to fix this is to add a filter on a pipe from a peer
table to the collector table to propagate only the routes from an
attached BGP protocol (and not the routes received transitively from
the master table).

BTW, why are you adding the collector table? It seems to me that 
you have same filters to the master table and to the collector
table so they would have the same content.

-- 
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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