[ovs-discuss] ovs-vswitchd disconnecting UNIX socket

[Ben Pfaff]

On Fri, Apr 22, 2016 at 11:25:26PM -0700, Ben Warren wrote:
> As you can see, the disconnects happen when the datapath ID changes,
> presumably due to adding interfaces?  Only the addition of the first
> two interfaces seem to bring it down.

OVS disconnects OpenFlow connections when the datapath ID changes
because the datapath ID is important to some controllers and OpenFlow
provides no way for a switch to notify a controller that the datapath ID
has changed.

> On the client side, I’m really confused.  As you can see, I re-open
> the connection with a HELLO message, and the HELLO response comes back
> with an earlier XID (0x80 vs. the expected 0x86).  Message 0x83 was a
> BARRIER response, and a valid BARRIER reply was received, so it would
> seem that messages after 0x80 were accepted:

HELLO is not a request/response message.  Rather, both sides of the
OpenFlow connection send a hello message at the initiation of the
connection.  Each side chooses its own xid as it wishes, so one cannot
expect the xids to match.  The xid for a hello message is only
significant for sending an OFPT_ERROR response, if necessary.