From: Roman Rodichev (rodic000@xxxxxxxxxxx)
Date: Sun Jun 03 2001 - 22:07:59 GMT-3
Do they exchange some information besides DATA? Somehow the receiving router
needs to know what to expect?
>From: Mas Kato <tealp729@home.com>
>To: 'Roman Rodichev' <rodic000@hotmail.com>, ccielab@groupstudy.com
>Subject: RE: RTP header compression
>Date: Sun, 03 Jun 2001 13:21:42 -0700
>
>At the risk of oversimplification, I would say the compression scheme is
>analogous to MPEG2, where for the most part, an uncompressed header is
>initially sent and then only the differences between subsequent headers
>is transmitted in the compressed headers. The streams are
>compressed/decompressed link-by-link and different streams are tracked
>by a "context ID."
>
>See RFC-2508 for all the gory details:
>ftp://ftp.isi.edu/in-notes/rfc2508.txt.
>
>Mas
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Roman Rodichev
>Sent: Sunday, June 03, 2001 12:06 AM
>To: ccielab@groupstudy.com
>Subject: RTP header compression
>
>
>This question was bothering me for a long time. RTP header compression
>reduces IP/UDP/RTP header size from 40 bytes to 2-4 bytes. I suppose
>that
>happens only each hop (between two adjacent routers). I still don't
>understand how receiving router will recognize what's in the packet?
>Does
>anyone know approximate header structure of the header-compressed RTP
>packet?
>
>IP header is 20 bytes.
>1-Version,1-TOS,2-Length,2-ID,2-Fragm,1-TTL,1-Type,2-Checksum,4-Source,4
>-Dest.
>If the header gets compressed down to 2 bytes (including UDP and RTP),
>how
>will receiving router identify that it is an IP packet, that it has
>protocol
>number 17 (UDP) and what the source/destination is?
>
>Is there a different Ethertype or something? I don't get it
>
>Roman
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