one way voice - teleworker

[michaelrogers]

There are loads of posts on this which i've read but i am seriously stuck and would appreciate some guidance.

Infrastructure:

Network split into 2 vlan's
Data network: 192.100.100.x
Voice network: 10.0.0.x
layer 3 switch routing between the 2 ip ranges (192.100.100.250 & 10.0.0.250 gw: 192.100.100.10)
192.100.100.10 - adsl router for internet access
All the pc's have a default gateway of 192.100.100.10.
The phones have a default gateway of 10.0.0.250
We also have another sdsl link for our teleworker & others

SDSL has 4 relevant ip address's (real wan ip's hidden)
x.x.141.129 - sdsl router (setup in no nat)
x.x.141.130 - Firewall
x.x.141.131 - Wan side of teleworker
x.x.141.132 - spare

There is a cat 5 connection between the router and the firewall to protect anything coming into the network and a cat 5 lead between the router and the teleworker to avoid it going through the firewall.

The Tw is setup in svr/gateway mode (int ip: 192.100.100.28, ext ip: x.x.141.131).

Problem

When a tw handset dials in we can hear them fine (incoming audio is fine) they cann't however hear an internal handset or any external number (outgoing audio isn't heard).

Now i thought it was to do with outgoing packets getting lossed across the adsl (192.100.100.10) as phone would route to 10.0.0.250 then that would route to 192.100.100.10. So i put a static route in the adsl router (192.100.100.10) which said (ip: x.x.141.128 255.255.255.248 gw: 192.100.100.28) If i do a trace the packets from my pc does follow that route.


Now this HAS been working in the past and then stopped recently. We thought it was to do with a powercut we had which knocked everything over, we also thought it was the router at 192.100.100.10 but we've swapped that back to the original.

Any suggestions anyone?
Is it possible with something like wireshark to monitor voip packets?
What would the packet header destination ip of the outgoing audio be? Would it be the wan ip of the tw handset?

Any help much appreciated...

 

[Mitelmatt]

What config is the teleworker in? Server only or Srver Gateway?

Is it in the data or voice network?

 

[michaelrogers]

Hi Thanks for the reply, it's in servergateway and is sitting in the data network.

Server Mode servergateway
Local IP address / subnet mask 192.100.100.28/255.255.255.0
Internet Visible IP Address 195.2.141.131
External IP address / subnet mask 195.2.141.131/255.255.255.248
Gateway 195.2.141.129
Additional local networks 192.100.100.0/255.255.255.0
10.0.0.0/255.255.255.0 via 192.100.100.250
DHCP server disabled

 

[kwbMitel]

The first thing I notice is that the TW server is sitting on the Data LAN and not the Voice LAN. This in itself is not a serious problem but it complicates things unnecessarily.

The issue is occuring because the GW at 10.0.0.250 is routing the return traffic to the TW set to the wrong internet connection. (routes to the Data Internet and not the TW server)

The best design is the have your TW server on the voice LAN

All sets and controllers will have their gateway set to be the internal side of the TW Server.

The TW server will have a local network added for the 192.100.100.x Network with gateway of 10.0.0.250.

With this setup, the TW server controls all the voice traffic and routes it correctly.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[michaelrogers]

ok seems sensible to be honest i'm not sure why it's on the data lan as it has no "data purpose".

Would you need to set a gateway on the tw? (not sure if you do or even can) what would you suggest it to be?

The data packet that comes from an internal phone to a tw handset, what destination packet would it have? The wan ip of the tw handset?

 

[kwbMitel]

The TW is set up normally with a Voice Lan IP and Gateway. The External Settings would not change.

The Local networks setting acts as a routing statement for all traffic destined to the Data LAN (for Management Typically)

If you have any other local networks that might need to talk to the TW server there should be a Local Network setting for each with the designated 10.0.0.250 Gateway as the routing destination.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[Mitelmatt]

It's no real problem sitting in the data vlan, but i would agree with kwbmitel, prob best practice to.

Whilst it's still in the data vlan though, go to Local networks and go to "Add Network" and input the voice vlan subnet (just remember it's says gateway in the add networks bit, that's the gateway address it usees to get to that subnet , so the data vlan gateway )

 

[michaelrogers]

Thanks for the replies guys i'm planning on moving it to the voice network tommorrow (Wed).

If it works or not i'll let you know.

 

[michaelrogers]

Fixed.

Moved the tw to the voice vlan on the 10 address range and set it in the dhcp scope to the new default gateway, deleted all the phone leases and reset all the phones. We then had 2 way voice between the handsets but we didn't have 2 way voice for outgoing or incoming calls.

MOdified the static ip settings on the phone system to route the same way and reset the phone system, this came back up and everything is now working.

Thanks very much for your help.

As a side note i found out that even teleworkers get a local lease from the phone system. I would guess this means that when routing packets to tw handsets they route to the local lan ip addy (leased through dhcp) via the tw that knows it needs to send them externally. Seems logical to me.

Thanks very much for your help.

 

[mitelmmaniac]

Hi I would also make sure you do what Mitelmatt suggested. Always add in local networks...That goes for any MSL based apps.

MM

Desk Jockey Lunacy

 

[LoopyLou]

Any time I have see issues with one way audio as described it is always issues with ports in the firewall or not defining the subnet the phones are on in the teleworker server. The internal sets have to be able to "talk" to the external address of the teleworker server. I have seen times where firewall have restricted this and the result is one way audio.

 

[kwbMitel]

The issue that was resolved in this case is not related to either firewalls or Local networks.

The fact is that the network has 2 potential routes to the internet. One for computer use and one for voice thru the TW server.

With the original setup, a routing statement would have been required in the local gateway to tell it to pass all traffic originating in the voice network and destined for a public address to the teleworker. Without said routing the gateway will route the packets to the internet via the Data connection and "voila" one way audio inbound only.

By moving the TW server onto the voice lan and directing all traffic to the TW as the gateway. The TW will then route according to its Local Networks settings and all is good.

Either scenario is valid but as I said at the beginning, Best Practice is to keep all voice traffic together.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.