[OpenAFS] Re: Ubik trouble

Harald Barth haba@kth.se
Tue, 14 Jan 2014 00:55:19 +0100 (CET)

> (...) This includes cases where one server has multiple addresses or
> interfaces on the same subnet.

Yes that was the case here. The puzzling thing was that it worked at
first, which probably means that the adress of B's outgoing reply
probably changed through time (urk). No I don't have tcpdumps from
back when it worked. Well, from the kernels point of view, any source
adress is good enough.

> The sad truth is that in order to properly support multi-homed hosts, Rx
> needs to be fixed so that it identifies all available interfaces, binds
> a separate socket for each interface, and keeps track of to which
> interface an incoming connection belongs, so that it can send responses
> out the same interface.

I don't know if it has to be sent out that interface (normally it
probaby will) but the responses need to have that source adress if I
understand that right.

Currently I have no multihomed Ubik servers (besides from the one that
should not have been, see above) and very few multihomed file servers.
So I can not say if the "rx breaks when routing is asymetric"
behaviour has given us any trouble for fileservers. At least not as
notable as this Ubik problem where I have shot myself in the foot real
good ;-)