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gilgameshau
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Help Please - QoS for VoIP over a WAN

Sat Sep 10, 2016 7:26 am

Hello,
I only know a little bit about networks so please bear with me.
I have two small sites that will soon have a VoIP service between them. That is, each site will have a VoIP gateway and use VoIP to talk to each other. They will not be using a 3rd party VoIP service. VoIP will not be used to make/receive calls from the greater internet. The router at each site is a Mikrotik RB2011.

I know VoIP should be on a QoS enabled network, and for the local environment at each site that is not a problem. The WAN connection between the two sites uses the same ISP but the ISP does not actually enable QoS in their network. As I understand it (and I could be wrong) once a QoS tagged VoIP packet transverses a network node that is not QoS enabled then it will loose any QoS priority from that point forward. So we won't have QoS between sites. Due to the remote locations and lack of a reliable service from elsewhere changing ISPs is not really viable.

Is there anyway of prioritising VoIP traffic in this situation? Would setting up a VPN between the two routers help?

Thank you
 
bvandenbremt
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Re: Help Please - QoS for VoIP over a WAN

Mon Sep 12, 2016 2:31 pm

QoS requires that it is configured end-to-end.
everything on internet does not respect your QoS.

If You really want QoS you should request an MPLS solution between the 2 locations from your ISP.

Configuring QoS on your VPN can help a bit to manage the traffic between the 2 sites but once on the internet QoS is lost.

Regards,
Bart


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mpreissner
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Re: Help Please - QoS for VoIP over a WAN

Mon Sep 12, 2016 2:47 pm

You may not have any issues at all using QoS. Many provider do state that QoS is not supported across the Internet, but especially if all your offices are on the same ISP, and you're using business class Internet service, QoS is likely enabled, but they won't tell anyone about it. Most ISP's now offer voice service themselves, and with business applications requiring greater reliance on real-time protocols for voice and video streaming, the simplest way for them to optimize bandwidth for their business customers is to implement QoS on their business networks. You can always run some tests to see if the QoS marks survive the trip between one location and the next. Even if they don't, the fact that all offices are on the same ISP means that you likely won't run into bandwidth issues, and you may be able to convince them to put all your offices in closer logical proximity to each other on their network, further reducing the need for QoS.
Michael Preissner
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sleerf
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Re: Help Please - QoS for VoIP over a WAN

Tue Sep 13, 2016 9:56 am

Who is the WAN solution provider and what is the WAN solution? Most true WAN solutions like MPLS honor QOS tags. If you are using plain internet with VPN, that's not really a true WAN service. If you have a company like Time Warner handing you a layer 2 connection or point to point, then your QOS tags are passed but ignored and will come out the other side. This is fine since the traffic entering and leaving each site should be already queued. The tough points for VoIP are at bottlenecks like your router. A 10M point to point or layer to ELAN is just passing the traffic from one end to the other without doing anything to it and there shouldn't be any bottlenecks in between the two ends. Generally in these cases they'll say they don't support QOS for a reason. They don't want the responsibility of troubleshooting QOS issues which are pretty much guaranteed to be on one of your two ends.

Even if you're just using internet with a VPN, you may be alright. It depends on the geographic location. Although they can't and won't support (ie troubleshoot) your QOS on an internet connection since they have no control over the internet, there's still a very good chance it will work because you have the same provider on both ends. There's a very good chance that the traffic never leaves your provider's internet egress point and instead stays on their network the whole way. Since they often support QOS for many other services, there's no sense in complicating things by intentionally stripping your QOS tags. Instead they are likely just ignored. This means that you may occasionally end up with quality issues when faced with bottlenecks such as shared service cable modems at peak periods where all the traffic is hitting the node at once and it doesn't care if your packet is QOS tagged or not, everything is going in and out first come/first serve.

As an enterprise telecom rep, this is a real pet peeve of mine. People often buy these VoIP systems and think "Hey, I can just get all these free calls!" and then run into trouble with call quality issues and blame the carrier, or VoIP in general. VoIP is intended to function on a controlled private network and then connect to the PSTN through a carrier where the traffic isn't co-mingled with internet data. The fact that it works over the internet is nice but comes with drawbacks.

If I were you, I would first just hook it up and see what happens. If you have trouble, call and get an engineer at your WAN provider on the phone and ask them if they strip the QOS or if they ignore it. If you are on a managed VPN or something I would ask about any other WAN or P2P options they may have. Don't talk to a sales or support rep. They will most likely be small business reps with limited products for small businesses. You want enterprise, major accounts, AE2, AE3, etc people who are the larger business people who sell complex products. I guarantee you if you called a Time Warner small business rep and said you wanted a layer 2 100M any to any private network or dark fiber, there's a 75% chance they wouldn't even know what language you were speaking.
 
mpreissner
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Re: Help Please - QoS for VoIP over a WAN

Tue Sep 13, 2016 7:44 pm

One way you could go is to procure a SIP trunk service from your ISP. Effectively, this will cause all traffic for your VoIP calls to go over a special network the provider uses specifically for VoIP. If you have an IP PBX at each site with SIP trunk service at each site, you should get great call quality.
Michael Preissner
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gilgameshau
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Re: Help Please - QoS for VoIP over a WAN

Wed Sep 14, 2016 2:28 am

Thank you everyone for your responses.
To answer a few questions that were raised.
This is in Australia. There are only two small offices in the one city of less than 30 people in total.
It is a not for profit charitable organisation that helps people in crisis. As such they rely on donations to keep operating so they are very aware of any outgoing expense. So they were also using the connections for internet access as they need to access various government web sites. A such I don't think a MPLS service is financially viable.
I will follow up and see if the SIP trunk option is available.
Thanks again for your help

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