[VOIPSEC] TLS and Firewalls

[Thomas Howe]

Michael -

Let me weigh in on that one.  A single port for transport has some
serious scaling and implementation issues.  A single port makes an
assumption that the media and control signalling are both going to the
same place.  Maybe that might be an OK assumption for an IP phone, but
what about any large scale device? Would you really have all the media
flow through the control processor, then out again into the media
processor?  That becomes very cumbersome, very quickly.

It also has a problem with disaggregation.  If you wanted to add an
speech detection system into your network, how would that work? Would
you put one into every IP phone? Or maybe you could come up with a call
control scheme that would hand off the call to another system.  Well, if
you completely handed off the call, how would you do billing and
authorization? Or, if you didn't, can you imagine the convoluted call
control ladders to get that done? And if you could, then try to scale
that puppy, and you could get a discount price on Tylonol for your
headache.

It would be so much simpler to send the RTP somewhere else for a while,
thus requiring a separate port for it. (Of course, two if you count RTCP).

This help any?

Tom



Michael Sandee wrote on 2/9/2005, 2:15 PM:

  > Brian,
  >
  > RTP and the problems surrounding firewalls, NAT/PAT have been around for
  > quite a few years, being it H323, SIP or...
  > Trying to globally solve this is a nice goal to set, but (apparently)
  > impossible to accomplish. There are workarounds like STUN which work
  > with _some_ devices.
  >
  > If one protocol comes forward which has some distinct advantages over
  > the alternatives, it cannot be considered a "Not Invented Here"
  > protocol. The advantages are not only a single port, but also trunking
  > and some other features which are very useful in a practical pbx
  > environment.
  >
  > Can you please elaborate on why exactly IAX is bad for choosing a single
  > port as transport?
  >
  > Michael
  >
  > Brian Rosen wrote:
  >
  > >Ultimately, this is the problem with IAX.  It's a special protocol,
  > >promulgated by a small group, without a rigorous process.
  > >
  > >It's not in the general interest of the Internet Community (whatever
  > that
  > >is) to have multiple ways to do the same thing.  SIP is the way the
IETF
  > >decided to do session management, including voice, video and text
  > (although
  > >there are other IM protocols).  IETF is not the only game in town, of
  > >course.
  > >
  > >I think that, actually, the IAX one port idea is a bad way to handle
  > >signaling and multiple media streams related to the same session.
  > The fact
  > >that it makes it easier on the firewalls is not enough to overcome the
  > >limitations it has.  We're better off working to make SIP and
  > firewalls work
  > >better together.
  > >
  > >Brian
  > >
  > >
  > >
  > >>-----Original Message-----
  > >>From: Voipsec-bounces at voipsa.org
[mailto:Voipsec-bounces at voipsa.org] On
  > >>Behalf Of Diana Cionoiu
  > >>Sent: Wednesday, February 09, 2005 12:09 PM
  > >>To: Alexander
  > >>Cc: Voipsec at voipsa.org
  > >>Subject: Re: [VOIPSEC] TLS and Firewalls
  > >>
  > >>If you find any RFC avaibile for IAX let me know. Until now we have
  > >>implement IAX based on what we have been able to learn from other
  > people
  > >>code. The problem with IAX secure is that of course there is no
  > standard
  > >>and we have to get all developers from different projects together and
  > >>"maybe" we are lucky enough to convince them to make it work right.
  > >>>From my experience each project has his own IAX version.
  > >>
  > >>Diana
  > >>
  > >>
  > >>
  > >>>>one port. The problem with IAX is that are no devices around. We
hope
  > >>>>
  > >>>>
  > >>that
  > >>
  > >>
  > >>>  There are some devices with IAX support, and the trend is, there
  > >>>  will be more soon. Just few of them:
  > >>>
  > >>>  http://www.iaxtalk.com/
  > >>>  http://www.digium.com/index.php?menu=iaxy
  > >>>  http://www.farfon.com/
  > >>>
  > >>>Regards,
  > >>>/Al
  > >>>
  > >>>_______________________________________________
  > >>>Voipsec mailing list
  > >>>Voipsec at voipsa.org
  > >>>http://voipsa.org/mailman/listinfo/voipsec_voipsa.org
  > >>>
  > >>>
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  > >>
  > >>
  > >>
  > >
  > >
  > >
  > >
  > >_______________________________________________
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  > >http://voipsa.org/mailman/listinfo/voipsec_voipsa.org
  > >
  > >
  > >
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