QoS on WRP400

Unanswered Question
Aug 26th, 2010

Hello , I had customer with the problem below any help is appreciated


"To explain to you the what we are trying to do with the WRP400 and the problems that we are having.


We are a Wireless ISP in Ireland and we deliver a broadband and VoIP service to our customers. For our residential customers that use our VoIP service we use the WRP400 at the customer premises as it has wifi but most importantly 2 build in ATA for the phone service.

On our network we have QoS set up using Difffserv and all VoIP our traffic is marked in both directions and we find this works well. The problem that we have been having with the wrp400's is that when a customer is on a call they get gaps with silence in the call. So what we mean here is that our customer using the WRP400 cannot hear the person at the other end of the call for periods up to 6-7 sec at a time.

We would normally expect for a customer to to have difficults with the upload of a voice service as out typical data package is 3072kbps down and 512kbps upload however in this instance the problem is on the download side. We put this issue down to a QoS at the start and when we connect an ATA (PAP2T) onto the same router (WRP400) and set priority on it then this problem was resolved and the voice quality was fine. However having deleted the QoS  config for the same router with the extenal ATA the phone worked fine.

When we came across this problem first we put it down to capacity issues on our network but having performed a number of upgraded on our network we noticed that this was not fixing the problem and we are confident that this is not a capacity issue on our network

As a result of the testing that we have done with the ATA (PAP2T) connected to the ethernet port on the same router (WRP400) we believe this is either an issue with QoS on the WRP 400 or it is an issue with the Build in Phone Ports on the WRP400.




I was hoping that somebody from Cisco could do some work on this problem with us to get is resolved and allow us to start using this great product (when it does what its surpose to do) again"

I have this problem too.
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Alberto Montilla Thu, 08/26/2010 - 03:13

Hi;

I suggest you check the following:

(1) What's the bandwidth utilization in downlink? For links that are around 2Mbps utilization, to ensure rigth Voice delays and jitter should not be higher than 60%. If the full pipe is used, this would generate additional jitter.

(2) Have you played with the jitter buffer size? This may help a bit if the situation is not bad.

(3) Use a more efficient codec, e.g. G.729 instead of G.711.

Traces would also help to see how the packets are being marked in the downlink. The amount of traffic is way lower than the max capacity of the WRP400, so this should not be an issue of the WRP400 (unless there is a bug, so I would vote for checking the above tests and see the results).

Regards
Alberto

tech_meister1 Fri, 09/03/2010 - 23:05

Hi

I don't know the answer to your problem, but I can tell you that you are not alone with this problem.

I have 2 of these WRP 400 routers in the hope of suppling an AIO solution for my VOIP customers.

How ever after my first install went horribly wrong when the customer complain that they could not hear the other party

with gaps in the incoming voice. The whole thing was a bit of a nightmare and I nearly lost the customer.

The customer had a  wireless broadband connection with 3000kbps up and down, so bandwith should not have been a problem.

I tried to fix the problem but never succeeded. I worked with the ISP and they also said that they trial some theses routers and had the same sort of

issues, so abandoned the use of them.

I finally fixed the problem with a SPA2102 which work very well even without QoS.

If they were still under warranty I would send them back to the supplier.

There have been a few firmware upgrades since then which I have done but so far the problem is still there.

I don't think Cisco will ever fix the problem and maybe it cannot be fixed by a firmware upgrade(could be hardware issue)

but to avoid a recall they simply ignore the problem.

I don't believe it is a QoS issue or even a nat issue as the VOIP does not go through the nat.

I have found if you reboot the router it could be ok for up to 2 months at a time, but then all of a sudden will start losing

RTP packets so resulting in voice gaps and only on incoming.

Do yourself a favor and dump the WRP400 for a SPA2102 or even a PAP2T.

Good luck

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