Remote extensions over VPN question

[Signo]

First off I would like to thank everyone for there time and suggestions. You have helped me greatly over the years.

So the question is how many remote 9608 sets would you be comfortable having over a VPN that has a 20 down 4 up connection on the remote side and a 30 down 4 up on the IPO side? There is no separate VLAN for voice as it was just 3 phones originally and the "IT guy" did feel it necessary.

Background info:

I have a customer who has a warehouse that was just supposed to be 3 9608 and a sip paging server. He is now wants to move some sales people to this remote site, who will be on the phone a lot. This was not part of the original plan pitched to me on the sale. I have had voice quality complaints already which were related to Comcast having a bottle neck when school lets out and the kids jump on the net. I really wanted to do two full systems, because all calls now traverse the network for dialtone and I don't think this is very efficient, they also remote to their production database on this connection adding to bandwidth consumption.

There are two different cable providers between the two sites, an my company is the provider on the IPO side which makes it nice because I can see bandwidth usage and know I am not bottle necked on that side.

 

[IPOfficeIreland]

without qos I wouldn't be happy putting 1 remote phone over a vpn. with proper qos you can put as many as you want. simultaneous calls is limited by your 3mb up (about 30 calls @ g711)

 

[Signo]

I forgot to mention the system is set to g.711 I read a rough estimate of 64k in the documentation. I am going to talk to the IT guy and discuss the need for qos and vlan for the sets if he wants reliable service.

I must admit I was pushed into this job by my employer and am new to the IPO side of this and appreciate your help.

Thanks for your help

 

[JayNEC]

It's important that you set expectations first. No matter how many/little VPN phones there are, there WILL be issues. VOIP over VPN will never be 100 percent as there is no chance of QOS.
DO NOT allow the customer to think otherwise. Even once you do that, they'll still complain about VOIP quality issues when they occur, but you can fall back on what you already told them.

Having said all that, "how many phones" really means "how many active calls". If these are call center people versus office workers there's a very different traffic load.

The 4 up is the bottleneck here, but even a 4Mb pipe can handle a LOT of calls - in theory ~133 active calls at G.729. Depending on your firewall you may be able to prioritize outbound traffic for VOIP which would be a great idea (and it's actually the only QOS you can do)

 

[JayNEC]

Also, a VLAN won't do you any good at all on the VPN/internet traffic QOS. It will only help if there are LAN issues.

 

[Signo]

OK that'w what I thought about the qos. I am a Central office guy normally and I know that once you hit the internet all bets are off as its a best effort delivery system with to many variables to be 100% reliable.

These are not call center people, but sales people and only 2 as far as I know, but they never tell the whole truth it seems. The rest of the phones are in places for convenience as workers are in diffident places in the building. As you pointed out the math works out that it should not be a problem. I have never seen a bandwidth number for the sets when they are idle and was wondering how much they consume just to keep alive verses active calls

I took the path you mention when the job was first done that this is the cheap way (VPN/ remote extensions) of doing this and that reliability and times would be and issue. I have a tendency to communicate the worst case so if it happens I am covered. I understand networking and such I just don't do these kind of jobs often and have no senior tech to bounce stuff off of. He got a case of the ass and quit leaving me holding the bag a while back.

Thanks for all the input and help

 

[JayNEC]

The idle on the phones is only measured in bytes per second. The occasional heartbeat as a "check in" really. It's really really low and not a concern...

 

[yankblan]

Your 64k for g711 is for voice only; when you put in the headers and the rest, round it up to 100k; like the other guy said, 30 active calls for 3MB. And that 3MB is a theorical figure the provider gives (you should know, right?) Plus, if it's cable or fiber versus DSL it makes a lot of difference. When I install this type of solution over DSL, I get in a foul mood.

http://interconnexionsld.ca/

 

[atcom]

The trouble with DSL is that the speed and consistency can vary greatly - even over the same connection. Sometimes it seems to be in a state of "constant re-negotiation" which is TERRIBLE for any VoIP. There's nothing you can do about it unless the Telco will send out a knowledgeable tech who can actually see, troubleshoot, and repair the issue (if possible - it could just be bad cable).

-----------------------------------
Calgary Telephone Systems, Avaya LG Asterisk (FreePBX) VOIP & TDM

 

[gwebster]

It is counterintuitive, but if you are running over a link without QoS then you should actually use G711 even though it uses higher bandwidth than G729. The rationale is that G729 is a compressed codec so already starts with a lower voice quality and degrades rapidly with any additional delay or jitter (which is going to happen without QoS).

 

[Optman]

If you use 9608, they don't support vpn client on its firmware, so you need to set up branch-to-branch vpn tunnel firstely (between two VPN Gateway). if not you can replace 9608 with sets that support vpn client firmware like 9620, 9630 or 9650...then you need only to set up branch-to-client tunnel so you will need only one VPN gateway on the main site and the avaya phones on the remote sites...

 

[Signo]

Yeah we already have a branch to branch vpn setup.

Jaynec if I have the it guy setup qos on the routers that would prioritize traffic across the VPN correct? I think they are going back remote to a sql server for production data and if we could prioritize the voice traffic over the data, in my mind that would help. We are still at the mercy of Comcast as far as far as there network saturation but that is out of our control.

I setup a test box in my office and have been messing with vlans a qos, but I am having trouble using one dhcp server as I cant get the traffic to from the voice vlan to hit the dhcp server that is on the data vlan. All I have to test with is a old nortel BES-120 and I dont see any place to put dhcp helper info in for the vlan to forward dhcp request to the server on a different subnet. This would be needed to seperate the traffic and allow pc's that are plugged into the phone to get addresses also is how I understand it.

I am new to the whole vlan part of this, I was CCNA certified a loooong time ago so the whole thing is not completely confusing, but it is not easy to following using sparse information off the internet.

How do you guys set this kind of thing up?

 

[madwok]

Hi,

If your customer is a Cisco shop, you might want to see if they want to turn on auto qos
Once auto qos is on, you can tweak it a bit on the Avaya side on the cos or dscp value so the Avaya phone can play nice with the Cisco . On the router, you also look at creating a strategy of how you want the prioritized voice traffic over normal data, providing the LEC is honoring the QOS . QOS is still a black art as you have to adapt to the customer environment . In your case, having site to site VPN is a big plus already . If you are CCNA , you should not have any problem with finding old 2620 router and couple 2950 setup DHCP and use router on a stick to config sub int for VLAN , should you want to play around with it. Just remember to give have voice vlan statement under the switch interface unless you want to use the old fashion trunking method. Please note that these equipment are obsolete by Cisco new standard but they are working fine in my very limited budget personal lab . Sorry that I don't know anything about Nortel data gear .

 

[Signo]

I got the vlans setup on the nortel and got a old p4 with fedora 17 on it doing the dhcp for the network the router is an old ddwrt unit I had around the house. I have option 176 and 242 in the dhcp server for the phones which are a 1616i and a 9608. Although I could just use option 242 I added both.

So far I have a 1616i that can connect get its info from option 242 change vlan which is vlan 2 in this case, once it changes I have the IPO doing dhcp for the phones and all is working well.

Now the 9608 is a different story, it will connect but will not change to vlan 2 it just keeps power cycling. The only thing I keep seeing is a DHCP ACK error with is strange.

Now to figure out how to use one dhcp server with 2 scopes for both vlans and why the 9608 does not like the configuration.