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Re: [Condor-users] Using STUN instead of the CCB
- Date: Tue, 19 Jan 2010 21:48:53 -0600
- From: Dan Bradley <dan@xxxxxxxxxxxx>
- Subject: Re: [Condor-users] Using STUN instead of the CCB
CCB doesn't do any forwarding of packets other than to inform daemon B
that daemon A wants to connect. Then daemon B connects to daemon A.
Presumably, A cannot directly initiate a connection to B because B is
behind a firewall or NAT.
Since CCB brokers TCP connections, UDP is not supported. All
communication from A to B that would normally be UDP in Condor is
therefore automatically switched to use TCP. In environments where STUN
works, we could avoid the overhead of TCP and continue to use UDP.
However, we have observed a lot of environments where STUN doesn't work
and we haven't been aware of any big problems caused by the use of TCP
in place of UDP. If you find some, please let us know!
Marc Tardif wrote:
I've been reading about the Condor Connection Broker (CCB) and my
understanding is that it provides a central point where two services,
like the scheduler and the starter for example, can exchange packets
if they are both behind firewalls. So, I was wondering if Condor also
considered using STUN  to achieve the same objective while having
the above mentionned "central point" incur significantly less bandwidth
overhead. The only difference with this approach is that it only works
with UDP, whereas CCB could also work with TCP. However, since Condor
already has the concept of a SafeSock, then this could potentially