Pipe collisions and missing IPv6 LL addresses

Ondrej Zajicek santiago at crfreenet.org
Tue Feb 1 14:37:50 CET 2011

On Tue, Feb 01, 2011 at 11:59:11AM +0100, Jerome Durand wrote:
> Hi all,
> I am running bird 1.2.5 as a RS using classical design (one table per  
> peer and one master global). I also added in addition a second table  
> called "collector" that is just populated as the master table with other  
> pipes protocols. Idea is that this table can be polled without touching  
> the master table (never know)
> 1°) Pipe collisions:
> --------------------
> I have this in my logs:
> 2011-02-01 10:32:50 <ERR> Pipe collision detected when sending  
> X.Y.Z.T/zz to table collector

Pipes and tables are originally supposed to form a tree, not a dag or
even a cycle, you have to set filters in a way that it is a tree from
a point of view of each route.

You probably have filters on pipe from a local table to the collector
table that accepts everything in and nothing out. In that case, if BGP
protocol A receives a route, it is added to the local table of proto A,
then it is propagated directly to the collector, also to the master
table, from that it is propagated to local tables of other BGP protocols
and from that again to the collector table (which forms a dag). You need
to set filters on a way to the collector table that only routes received
directly from a BGP protocols (not routes received through pipe from the
master table) are propagated to the collector.

BTW, there is not a much difference between polling the master table and
the collector table, i don't see a point in that, unless you want do set
a different filters.

> 2°) Missing LL IPv6 addresses:
> ------------------------------
> I also have some problems with few IPv6 peers which seem not to send me  
> LL addresses.
> 2011-01-31 16:48:12 <ERR> R655687: Missing link-local next hop address,  
> skipping corresponding routes
> 2011-01-31 16:48:12 <ERR> R655687: - route xxxx:yyyy::/32 skipped
> xxxx:yyyy::/32 being a regular IPv6 prefix.
> The weird thing is that this peering is also flapping... The customer  
> tells me he has the same config with other peerings without any problem.  
> Any hint? Is bird doing more verifications than some vendor routers?

You need option 'missing lladdr ignore' in BGP protocols.
See documentation for details.

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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