From: Nouman Ahmed Khan (nouman.khan@mis.com.sa)
Date: Mon May 15 2006 - 06:44:48 ART
Dear Larry
RTP header compression compresses the IP/UDP/RTP header in an RTP data
packet from 40 bytes to approximately 2 to 4 bytes . This compression
feature is beneficial if you are running VoIP over slow links. Enabling
compression on both ends of a low-bandwidth serial link can greatly reduce
the network overhead if there is a lot of RTP traffic on that slow link.
You should configure RTP header compression if the following conditions
describe your network:
. Links slower than 2 Mbps
. Need to save bandwidth
If you include the passive keyword, the software compresses outgoing RTP
packets only if incoming RTP packets on the same interface are compressed.
If you use the command without the passive keyword, the software compresses
all RTP traffic.
I hope that helps.
Regards,
Nouman Khan
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Larry Chuon
Sent: Sunday, May 14, 2006 9:01 PM
To: ccielab@groupstudy.com
Subject: RTP Compression Header
Hi Group,
I'm play around with command "ip rtp header-compression". After reading
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120
t
/120t7/rtpfast.htm,
I'm still unsure its purpose. Can someone please shed some light on this?
From what I gathered, this command can also be used on frame-relay interface
as well. Under what circumstance do I need to use this?
Also, in help mode, I show "passive" option. Does it work similarly to a
passive interface?
r6(config-if)#ip rtp header-compression ?
ietf-format Compressing using IETF format
iphc-format Compress using IPHC format
passive Compress only for destinations which send compressed
headers
periodic-refresh Periodic context refresh
TIA,
Larry
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