From: Kumar Raja-Q16843 (Raja.Kumar@motorola.com)
Date: Mon May 15 2006 - 01:58:48 ART
Larry,
Some more inputs on a practical network, where it has been used.
Alright, this is where we use the compression in our network, while
transporting the real time (Voice) packets from a BTS to the Central
Switch, this you may compare to a remote office where you have IP
Telephone and central office having the Call Manager.
Wireless voice packets typically have payload portions that are smaller
than the accompanying IP/ UDP headers (e.g. 20 bytes compared with 28
bytes). It is highly inefficient to send such a packet over a slow link
without compressing the headers. Typically, the 28 bytes can be reduced
to as few as 2 bytes (4 with UDP checksums). The basic idea behind the
compression relies on the fact that, for a given flow, many of the
fields in the headers are either constant, or the difference from packet
to successive packet is constant.
Hope you get the idea, let us know, if you need any further details.
Thanks and regards,
Raja
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian Dennis
Sent: Monday, May 15, 2006 3:49 AM
To: Larry Chuon; ccielab@groupstudy.com
Subject: RE: RTP Compression Header
Larry,
This link should help out.
Compressed Real-Time Protocol
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configur
ation_guide_chapter09186a00800b75cc.html#wp1000925
Remember that you should understand the technology or feature
before you start configuring any thing. I cover this exact issue in an
article I wrote about how to pass the CCIE lab. It's under the "Three
Step Learning Process" section.
http://www.internetworkexpert.com/resources/ccielab.htm
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Larry Chuon
Sent: Sunday, May 14, 2006 11:01 AM
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
/120t
/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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