[nsp] VoIP on a Cisco 7513

Lucas Iglesias l.iglesias at tiba.com
Mon Jul 28 13:57:36 EDT 2003


Hi everybody,

We are having problems with VoIP priorization on a 7513. 
The situation is simple, we have a 7513 with 2 PA8T, a PA-2H and a FEIP2.
Our customers are connected to the PA8T serial interfaces with satellite
links, which some of them have to be configured to priorize VoIP packets (we
use PPP Multilink and LLQ with ip rtp priority or a policy-map).
Here is a typical configuration of the Multilink interface:

interface Multilink2
 bandwidth 128
 ip address 192.168.1.1 255.255.255.252
 load-interval 30
 no cdp enable
 ppp multilink
 ppp multilink fragment-delay 10
 ppp multilink interleave
 multilink-group 2
 ip rtp priority 16384 16383 40
end

The problem is that the priorization is not working properly, gaps appear
when the link is also used to download a web page, etc. If we make a change,
and receive the carrier through a 2600 (or 2500,7200,805) and connect it to
the 7513 through Ethernet, the voice quality become good, without gaps
(belive it or not, VoIP over satellite links works good).
We've found a BUG (CSCdw83924) related to all 12.1 IOS versions saying that
LLQ was not working on 7500 platforms, so we updated the version to
12.2(16b) which is working better, but anyway the voice quality is not good
enough. 

Any kind of help would be appreciated.
Thank you !
========================
Eng. Lucas Iglesias 
IP Engineering, Tiba S.A. 
========================


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