[Freeswitch-users] TCP vs UDP SIP

[Jeff Leung]

> Hi Jeff,
> Thanks for the insight.  Forgive my ignorance but if I have two Identical
> Freeswitch servers with SRV records and endpoints that properly support
> SRVs, why do I loose the ability to failover if one host is not reachable?

TCP is a stateful protocol. On the other hand UDP isn't, it's stateless.
It's just easier to failover with UDP than with TCP if you understand the
difference between the two protocols. I'm not saying that it's not possible
to do so with TCP, but with the way how SIP works, you'd want to use UDP if
you want failover capabilities without the headache.

> Also as many of these end points are Polycoms behind NAT, I can't see any
> reason I'd still need NDLB-force-rport on the profile?
> 

Unfortunately, I don't work with Polycom phones. Brian West over here can
comment on that issue.

> Since these are application servers, handling conferences, presence, etc.,
I'd
> imagine I would hit other bottlenecks before I hit the TCP connection
limit.

Yes that's true, but if you had a FreeSWITCH box that purely handled SIP
messages and no media, you'd probably hit that TCP Open connection limit.

> On May 8, 2013, at 9:51 AM, "Jeff Leung" <jleung at v10networks.ca> wrote:
> 
> >
> >
> >> -----Original Message-----
> >> From: freeswitch-users-bounces at lists.freeswitch.org
> >> [mailto:freeswitch- users-bounces at lists.freeswitch.org] On Behalf Of
> >> Vik Killa
> >> Sent: Wednesday, May 8, 2013 9:18 AM
> >> To: FreeSWITCH Users Help
> >> Subject: Re: [Freeswitch-users] TCP vs UDP SIP
> >
> > That I would agree with, but the thing is you lose the capability of
> > failover in the unlikely event that a node in a FreeSWITCH cluster fail.
> >
> >> In my opinion, TCP seems better than UDP as you know all the SIP
> >> packets are making to their destination.
> >>
> >> On Wed, May 8, 2013 at 11:37 AM, Jeff Leung <jleung at v10networks.ca>
> >> wrote:
> >>
> >>
> >>    On a Linux system there is a limit of how many open TCP
> >> connections you have.
> >
> > If I can remember correctly, I think Darren from 2600hz did discuss
> > about the limit of open TCP connections you can have on a Linux
> > system. Correct me if I'm wrong on this, but that seems to be the
> > case. And I have seen instances of that happening on a misconfigured
> > Squid Proxy
> >
> >> I never heard this before...where and how it this limit defined?
> >>
> >>
> >>    Unless you have a crazy amount of endpoints you have to serve, TCP
> >> probably isn't really worth it in my opinion.
> >
> > Assuming it's one Open TCP connection per endpoint,  you'd probably
> > need more endpoints than the maximum amount of open TCP connections
> to
> > hit that problem
> >
> >> How many endpoints?
> >>
> >>
> >>    Also did I also mention that TCP connections don't really fix NAT
> >> issues?
> >
> >
> >
> >
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> > 
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