Linux IPv6 routing strange behaviour

Jeroen Massar jeroen at
Wed Aug 14 16:09:17 CEST 2013

On 2013-08-14 12:58 , Max Tulyev wrote:
> On 14.08.13 13:39, Jeroen Massar wrote:
>>> I see the strange behaviour of my Linux routers. There are quagga and
>>> bird with IPv6 BGP full view.
>> On the same box? Are they using the same routing table? I am fairly
>> confident that will end up in a fight.
> No! Some boxes have Quagga, some - Bird, not together of course.

And are these boxes interconnected and are they thus possibly forwarding
the information to each other?

>>> Quagga/bird reports about 13500 prefixes,
>>> but route table constantly grow up to 100000 routes and more.
>> Which prefixes, and who/what originates them?
> The prefixes from the global IPv6 routing table. It should be one
> routing entry per route, but have the lot of totally same route strings.

Your view on 'global' will be different than that from any other person
depending on the peers you have, configuration settings and lots lots more.

Without details, little that can be stated though.

Note that my teeny Quagga box receives multiple full feeds, though does
not install them in a FIB, and has been running fine for over 10 years
(except for some strange lockup bug once in a while, likely caused by
multiple connections appearing/disappearing at the same time or some
other odd and non-easily-reproduceable race condition)

>> Are you maybe causing a routing loop towards yourself?
> I checked - no, but why a lot of routing entries, even if loop?

People cause bugs? And if the path does not contain repeated ASNs it
will nicely loop till something stops it.

>>> Did anyone see something like that? How I can fix it?
>> Providing outputs/log files would be a good start for people to look at it.
> Which logs can explain something?

The ones on your hosts? The ones generated by the tools that apparently

Of course it depends all on how you configure things, nobody can guess
what your setup looks like or how it is acting.

> P.S. It seems if there is more IPv6 traffic - there is faster growth of
> routing table.

One would hope so. Though at one point it will slow down, till
companies/end-sites start getting PI prefixes...


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