| Status: |
Individual Internet Draft, version 02 |
| Date of last update: |
July 20, 2001 |
| Authors: |
J. Rosenberg, H. Schulzrinne |
| Current Document: |
draft-rosenberg-sip-entfw-02.txt |
| Summary: |
In this draft, we discuss how SIP can traverse enterprise and
residential NATs. This environment is challenging because we assume
here that the end user or SIP provider has no control over the NAT,
and that the NAT is completely ignorant of SIP. Our approach is to
make SIP "NAT friendly", with a few minor, backwards compatible
extensions. These extensions allow UDP and TCP-based SIP to traverse
NATs. We also handle RTP traversal using a combination of symmetric
(aka connection-oriented) RTP and a new NAT detection and binding
discovery mechanism. The results of the approach are that direct
UDP-based RTP is used whenever provably possible in any given nat
configuration. We use a network intermediary - in our case, an off-
the-shelf router - to handle the case when both caller and called
party are behind symmetric NATs. Our approach for binding discovery
is effectively a pre-midcom solution that allows binding allocations
by talking to a server behind the nat, rather than talking to the nat
directly.
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| Archive of older drafts: |
- Individual Draft -01,
March 2001
- Individual Draft -00,
November 2000
|