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routeros with VOIP and Wireless

Thu Apr 15, 2010 3:01 pm

hi Guys

I need some advice,

We have quite a large network, im one of the techs trying resolve

we have a wireless link directly into the voip providers backbone, also the voip ip ranges is routed directly from their datacenter. This is to avoid NAT problems

each client gets a unique voip range routed seperately for the the provider

we use queue trees on the edge(tower) routers to give each voip range a specific speed, eg, 128k voip is a 4 channel quintum sip gateway at client into their switchboard

This was working flawlessly until a week ago, We peak at about 2mbit of voip traffic at the main wireless link going in

we used a 433AH tower side with r52 radios to provider side, a 411 with r52, signal is -48, throughput tests was 27mbit one way on 5.8Ghz, cpu never peaked more than 35%( client side ) , 10%(tower side)

Now the problem, The initial call starting to get delay for 3 packets, so the sip session has to resend INVITE packets to the sip client - this is info from the providers SER server, they also helping from the datacenter side. The clients with asterisk servers, get a all circuit busy when they dial, then the 2nd time they try goes through

Also the provider seem only having a problem from the wireless link from us, clients from the internet is fine

Now what we have tried and found:

We replaced wireless links first with 2 x bullet M5 in bridge mode with a 750 on tower side and bulletm5 provider strait into his cisco( i suggest firmware upgrade as its on IOS V 12.3)

We have a -40 signal with airmax enabled, test the link we get 80mbit tcp through test, everything is 100%

we replaced switches, also the problem start at 9am and goes away around 4-5pm, so is a peak hour thing

we mark packets with ip firewall filter provider side and tower side and matched the packets to compare, results shows the same to udp port 5060 to a speicific host

we replaced the fibre converter coming from POE on roof down to datacentre as we not allowed to bring utp into the datacenter(has to be fibre)

we used a client directly connected to tower on a sector with a -60 signal to test and it still has problems, so its one hop away from provider

I keep suggesting to upgrade the cisco IOS first as its quite a old router( dont know model name )

also the provider has another sub provider which comes to diffrent server which is expierencing same issues through the wireless link

be aware there is cisco router between our wirelses and the providers's server , just for our wireless

So we establish its between tower and provider, but the links is replaced already and bridge instead of routed with MT

Provider uses codec g729 with 60ms payload

Now what we gona keep on trying:

use a sip phone and trace behind each router the call quality and problems.

bypass cisco and bridge from tower to providers core switch as a test

rest i dont know yet, hoping someone can help me here

I might have left some stuff we tested out, but hoping for some advice

Thanks

S
 
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nest
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Re: routeros with VOIP and Wireless

Thu Apr 29, 2010 3:43 am

I don't see any tests to determine if the channel chosen for the link is interference free. All you have done is examine the networking side. From your description there has been little attention to the RF side.
 
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tgrand
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Re: routeros with VOIP and Wireless

Thu Apr 29, 2010 4:53 am

Siganal strength of -48 is quite HOT let alone -40.
I would recommend you try to lower your output power to get to -58 to -64 range.

This may or maynot solve your problem, but will most certainly elimate one contributing factor.

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