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RE: Compression mystery posted 03/13/2003
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Hey Tim,

Looks like you are right... the IOS says that means compressing with "IPHC
format"  =)

Anyway, thx for that.


-----Original Message-----
From: Ouellette, Tim [mailto:tim.ouellette@xxxxxxx]
Sent: Thursday, 13 March 2003 12:05 AM
To: Hunt Lee
Subject: RE: Compression mystery

Yeah, I think if you turn on RTP header-compression with the iphc-format
tag, it'll turn on TCP header compression for you.

Thanks the only thing I could find out about it?


-----Original Message-----
From: Hunt Lee [mailto:huntl@xxxxxxxxxxxxxxxxx]
Sent: Tuesday, March 11, 2003 6:40 PM
To: 'Ouellette, Tim'
Cc: 'ccielab@xxxxxxxxxxxxxx'
Subject: RE: Compression mystery

So what's the use of "ip tcp header-compression iphc-format"?

Is it just for compressing tcp "data" traffic?

-----Original Message-----
From: Ouellette, Tim [mailto:tim.ouellette@xxxxxxx]
Sent: Wednesday, 12 March 2003 12:19 AM
To: 'Hunt Lee'; ccielab@xxxxxxxxxxxxxx
Subject: RE: Compression mystery

Voice traffic is a UDP data stream in the range of 16384 - 32676 even(this
is RTP)
but there is RTCP (control) that runs in the same range (odd)
As far as that "IPHC-format" goes, I did a search on cisco and it appears
when you type in "ip rtp header-compress iphc-format" that i'll
automatically add the "ip tcp header-compress iphc-format"...

The only TCP I can think of that would be flowing would be SSCP (skinny)
keepalives between your CCM and your IP phone?


-----Original Message-----
From: Hunt Lee [mailto:ciscoforme3@xxxxxxxxxxxx]
Sent: Tuesday, March 11, 2003 6:11 AM
To: ccielab@xxxxxxxxxxxxxx
Subject: Compression mystery

Hi Group,

I saw the following config from a VoIP config...

Would you know what is the differnece between "ip tcp header-compression
iphc-format" & "ip rtp header-compression iphc-format"?

Is it the first one is used to compress TCP "data" traffic, whereas the
latter one
is used to compress "RTP traffic" e.g. voice?

interface Multilink1
 ip unnumbered Ethernet1/0
 no ip directed-broadcast
 ip tcp header-compression iphc-format  <--- This?
 no ip mroute-cache
 fair-queue 64 16 0
 no cdp enable
 ppp multilink
 ppp multilink fragment-delay 10   
 ppp multilink interleave          
 multilink-group 1
 ip rtp header-compression iphc-format   <--- & this?
 ip rtp priority 16384 16383 48

And what does iphc-format do?

Any help / ideas would be greatly appreciated.

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