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pjulian
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Voice (VOIP) issues

Wed Sep 29, 2010 7:48 am

Hi guys, we currently run an RB1000 in our core network, we have about 50 DSL tails terminating on an LNS which then go into a VRF separate to our router. This then feeds into our router and on the other side we have some servers and an Elastix PBX which we use to provide trunks to customers for their PBX's.

We are having serious problems with voice quality which we just can't seem to track down.
For customer using a trunk we supply a dedicated DSL circuit, so we don't have data issues on that side, the problem is that the customers get choppy voice most of the time, sometimes it's fine, but mostly it's not.

The router is only just ticking over at around 3-6Mb/s and our carrier swears that their network is all good.

Everybody is telling me to ditch the Mikrotik and put cisco in, I have used MT's for years and like them, but I am concerned that perhaps this RB1000 is not handling the SIP traffic properly.

I have disabled all rules, mangling, queues, etc, it's really not doing much at all and this is getting very frustrating.

I am going to get a cisco configured up today and put in there tonight to replace the mikrotik, but I am keen to hear from anybody who has had any voice quality issues with traffic going through a routerboard and what they could do to rectify it if anything as this is a seriously bad problem for us now as we are just about to start losing our customers

Thanks for your help

Regards
Paul
 
riaanmaree
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Re: Voice (VOIP) issues

Mon Oct 04, 2010 11:46 am

Have you tested the Cisco router yet? I'd like to know if it made a difference.

Choppy voice calls it usually not because of speed/throughput problems, but because of jitter (differences in ping/latency). Try running pings to the different customers and other end-points on the network while there's traffic on it. On our network we had 3-4ms pings, but when there's 2Mbps traffic on some links, the pings jumped from 15ms to 180ms. This causes VoIP packets to arrive at the other and in the wrong order and chops up the voice.

I know some people fix this by setting a larger "jitter buffer" on Asterisk. This adds a bit of a delay to calls, but it MUCH BETTER than not being able to speak at all.
 
pjulian
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Re: Voice (VOIP) issues

Mon Oct 04, 2010 11:58 am

Thanks for the comments, actually I just removed the Cisco today as there was no difference.
Unfortunately the voice people I have troubleshooting do not know anything about Mikrotik, and although I was confident that there shouldn't be an issue I was not 100% sure, so this was the only way to be 100% sure and to prove to them that it was OK.
I will be upgrading to an MPLS core with some RB1100's if they ever arrive, but right now I am pretty confident that the RB1000 was not contributing to the problem.
It looks like the issue is either with the Elastix install we have, which we have re-installed onto another box even, or the SIP gateways we are talking through.
The voice guy just built a basic Centos/Asterisk box last week and it seems to be a lot better, if not perfect, we have cut one customer over to this new box and will see how they go for a day or two, so if it's elastix I'm pretty disappointed, it seems so good, maybe it's just not meant to be a softswitch, but as a pbx it's probably fine, time will tell as we have been installing that as pbx software for customers as well.

Regards
Paul
 
alex_rhys-hurn
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Re: Voice (VOIP) issues

Sun Apr 17, 2011 8:36 pm

Sorry to bring up an old post, but did you ever make progress with this? I have a very similar problem.

RB100 Router, and Elastix PBX using SIP trunks to two different providers.
 
sewlist
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Re: Voice (VOIP) issues

Mon Apr 18, 2011 9:03 am

Not sure what kinda issues u guys expierencing, but we run quite a large voip network with mikrotik into our voip provider

call quality was fine, but the call session setup was the problem .

We disabled sip helper on ALL our routers,seems to be problem at certain volume, we did not even have nat on our network for voip, but /ip firewall service-port disable sip did it for us, that little bugger cost us alot of business and about 2 months to track down.

My 2 cents

Sew

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