Subject: Header Compression Error Recovery

From: Mark Llacuna <[email-masked]>
Date: Wed, 14 Jul 1999 17:28:05 -0700

Hello everyone,

	I have  a few questions as to how an implementation of RTP header
compression would behave in case an out-of-order packet is received.  The
RFC (2508) specifies that if for example the first three compressed packets
were OK but instead of the fourth packet, the fifth packet was received by
the decompressor, the decompressor would invalidate the context and send a
CONTEXT_STATE packet.  The question therefore is:

	a) does the decompressor keep the first three packets?
	b) does the compressor send the fourth packet ( based on the
sequence number in the CONTEXT STATE packet )? and resend the fifth packet?
	c) if for example, there are several packets ( say 5,6,7,8 ) that
were received in the interim ( before a new FULL HEADER ) is received, what
is the heuristic used for resending a CONTEXT_STATE packet?  Or do you
actually just set a timer until a FULL_HEADER is received and resend a
CONTEXT-STATE?
	d) in case you use timers for c), what would be a recommended
timeout period?

	Any answers would be really useful.

Regards,
Joey Salanga

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