From: Larry Chuon (lchuon@gmail.com)
Date: Mon May 15 2006 - 08:00:49 ART
Hi Group,
Thanks to those who responded. After reading your comments and links, I now
have a much better understanding of the subject.
Dennis,
I should not have any trouble working on IEWB Lab 5 now. :)
On 5/15/06, Kumar Raja-Q16843 <Raja.Kumar@motorola.com> wrote:
>
> 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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