[ofa-general] iWARP issues

[Caitlin Bestler]

On Nov 2, 2007 4:02 AM, Talpey, Thomas <Thomas.Talpey at netapp.com> wrote:
> At 05:57 PM 11/1/2007, Sean Hefty wrote:
> >Does anyone know the details regarding the TCP connection retry algorithm in
> >Linux?  (time between retries, number of retries, etc.)
>
> Sure. The time between retries is variable, it starts out as a few seconds
> (think, three), and backs off exponentially for a variable number of tries
> (/proc/sys/net/ipv4/*retries*). It comes out to a pretty large number,
> a minute or two typically.
>
> You really don't want to depend on any of this however. TCP will use all
> sorts of information from other connections, routing table entries and
> congestion algorithms, etc to be as adaptive as it feels it needs to be.
> Constants are NEVER a good idea in networking.
>
> Why wouldn't you just leave the timeout to TCP, and make CM's infinite?
>

I agree that TCP should handle the timeout on TCP connections. Even if
there are two TCP stacks I see no reason for two TCP connection timeout
policies.

But the CM may want  to timeout the MPA Request/Response exchange
at least slightly more promptly than TCP would timeout an established
connection.

This probably is not urgent until iWARP is sufficiently deployed to attract
DoS attacks, but it would not be a good idea to lock in an absolute  "all
timeouts are handled at the transport layer" policy for the iWARP CM.
The gap between connection setup and connection visibility will eventually
make an inviting target.