Subject: [midcom] Unidirectional RTP!

From: "Rahul Gulati" <[email-masked]>
Date: Mon, 30 Dec 2002 18:43:25 +0530

Hi,

I am investigating into how RTP can be addressed through NATs and firewalls.

Some of the solutions mention using bi-directional RTP.
These need extensions to SDP, or using STUN/TURN where STUN clients residing in SIP-end equipment will need to send a request to the STUN server to get UDP NAT-bindings for RTP.

I had a few questions:

1) Is it possible to use uni-directional RTP in any of the above approaches?
2) If yes How?, Are there any sample call flows/drafts which I can refer for the same?

Would appreciate any help on this...

Best Regards'
Rahul

---

From: "Pyda Srisuresh" <[email-masked]>
Date: Mon, 30 Dec 2002 07:41:48 -0800

Well, the goal of the WG has been to come up with a MIDCOM protocol
that would make RTP possible through NAT and firewall.

regards,
suresh
  -----Original Message-----
  From: [email-masked] [mailto:[email-masked]]On Behalf Of
Rahul Gulati
  Sent: Monday, December 30, 2002 5:13 AM
  To: [email-masked]; [email-masked]
  Subject: [midcom] Unidirectional RTP!

  Hi,

  I am investigating into how RTP can be addressed through NATs and
firewalls.

  Some of the solutions mention using bi-directional RTP.
  These need extensions to SDP, or using STUN/TURN where STUN clients
residing in SIP-end equipment will need to send a request to the STUN server
to get UDP NAT-bindings for RTP.

  I had a few questions:

  1) Is it possible to use uni-directional RTP in any of the above
approaches?
  2) If yes How?, Are there any sample call flows/drafts which I can refer
for the same?

  Best Regards'
  Rahul

---

From: "Cullen Jennings" <[email-masked]>
Date: Mon, 30 Dec 2002 17:02:23 -0800

I think that STUN will work the same with unidirectional RTP as it does
with bidirectional RTP (that is to say it will work with man NATs but
not all)

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Rahul Gulati
Sent: Monday, December 30, 2002 5:13 AM
To: [email-masked]; [email-masked]
Subject: [midcom] Unidirectional RTP!

Hi,

Some of the solutions mention using bi-directional RTP.
These need extensions to SDP, or using STUN/TURN where STUN clients
residing in SIP-end equipment will need to send a request to the STUN
server to get UDP NAT-bindings for RTP.
 
I had a few questions:

 
Best Regards'
Rahul

---

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 31 Dec 2002 00:30:53 -0500

inline.

> Some of the solutions mention using bi-directional RTP.

I think perhaps you mean what has been called "symmetric RTP", where one 
side sends media to the source IP/port where it received media from the 
other side.

> server to get UDP NAT-bindings for RTP.

The usage of STUN is orthogonal to symmetric RTP. If you use symmetric 
RTP, and both sides are behind NAT, only one side needs to use STUN. 
With regular RTP its both.

> 1) Is it possible to use uni-directional RTP in any of the above approaches?

If you define "uni-directional RTP" as RTP where each side sends RTP to 
the IP/port advertised by the other side in SDP, then you can use that 
RTP along with stun of course.

> 2) If yes How?, Are there any sample call flows/drafts which I can refer 

The current repository of SIP/nat related flows is:
http://www.ietf.org/internet-drafts/draft-ietf-sipping-nat-scenarios-00.txt

its a bit out of date, but should prove a good start.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
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