cisco rtp header-compression 1

[alapi]

Hi,

I've a problem with ip rtp header-compression.
I've configured a Frame Relay link from 1811 to 1811, and i've configured the RTP header compression.

The main site is A and I've have only one phone in site B.

The header-compression work fine in some situations: call from phone in site A to phone in site B, or phone from site B to phone in site A.

But header-compression doesn't work fine when i call from phone in site B to CME in site A. It's only works IN ONE WAY. I watch the printout of command show ip rtp header compression, i see that matched packets in one way increases, and matched packets in the other way stay fixes.

RTP/UDP/IP header compression statistics:
 DLCI 20         Link/Destination info: point-to-point dlci
  Interface Serial0/0/0.20 DLCI 20 (compression on, Cisco, RTP, passive)
    Rcvd:    430940 total, 428075 compressed, 15 errors, 21 status msgs
             11 dropped, 0 buffer copies, 0 buffer failures
    Sent:    135815 total, 132998 compressed, 15 status msgs, 4378 not predicted
             4802689 bytes saved, 18321226 bytes sent
             1.26 efficiency improvement factor
    Connect: 256 rx slots, 256 tx slots,
             21 misses, 0 collisions, 0 negative cache hits, 256 free contexts
             99% hit ratio, five minute miss rate 0 misses/sec, 0 max

This is my configuration of frame relay.

interface Serial0/0/0
 no ip address
 encapsulation frame-relay
 frame-relay fragment 250 end-to-end
 service-policy output my-QoS-Policy
!
interface Serial0/0/0.20 point-to-point
 bandwidth 512
 ip address 192.168.51.2 255.255.255.0
 frame-relay interface-dlci 20
 frame-relay ip tcp header-compression passive
 frame-relay ip rtp header-compression

Thanks for help.
BR // JI

 

[BuckWeet]

One thing through the years I found out with RTP header-compression is that the UDP port numbers have to be within 16384 and 32767.. I experienced one-way characteristics like you until I corrected the port #'s..


BuckWeet

 

[alapi]

Hi BuckWeet,

I think it's happening that you tell me.

Thanks a lot of.

BR // JI

 

[burtsbees]

Give that man a star!

Burt

 

[alapi]

A star for BuckWeet !!

 

[BuckWeet]

Hope that helps you out.. I smacked my head over and over until I stumbled onto the port# requirement.. I don't believe its documented very well. When I was doing it, I was testing AVAYA VoIP and Cisco VoIP.. The Cisco solution would always compress yet the AVAYA wouldn't.. Turned out to be the UDP port# mismatch.. AVAYA by default uses between 2065 and 65535 I believe. Nailing the AVAYA UDP ports between the ones I posted previously caused its RTP headers to be compressed..

BuckWeet