RE: [Srtp-users] Comparison of SRTP vs. RTP over VPN

[David A. M. <mc...@ci...>]

Tony,

> -----Original Message-----
> From: srt...@li...
> [mailto:srt...@li...]On Behalf Of Tony Cheung
> Sent: Sunday, October 27, 2002 11:11 PM
> To: srt...@li...
> Subject: [Srtp-users] Comparison of SRTP vs. RTP over VPN
>
>
> Hi,
>
> I am new to the SRTP protocol.
>
> I would like to know if we could use RTP over VPN to achieve the
> security measures provided by SRTP. Is there any comparison out there?

RTP over IPsec ESP is possible, but can be quite bandwidth-inefficient due to
the extra headers in IPsec, the ESP encapsulation overhead, and the fact that
cRTP (RTP header compression) is no longer possible.  For voice-over-ip, these
inefficiencies are quite significant; RTP with a g.729 codec has a 20 byte
payload that can be dwarfed by as much as 80 bytes of ESP overhead.  Bandwidth
conservation is less of an issue for video packets, though some video systems
need to avoid encapsulation overhead so that they don't fragment (since their
packets are right at the MTU size).

RTP can't be run over TLS or SSH, since those protocols only work for TCP
connections.

David

>
> Thanks a lot.
>
> Tony Cheung
>
>
>
>
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