Howto:Different voice and data VLANs with innovaphone ip phones IEEE 802.1Q

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Contents

Summary

Many installations choose to run IP phones in a separate VLAN from the one used for PCs. For PCs connected to the IP phones "PC" switch port, special care has to be taken.

Applies To

This information applies to

  • all innovaphone IP phones with 2 Ethernet ports

More Information

Problem Details

In this configuration, both the Ethernet packets to/from IP phone and those to/from the PC will flow through the same switch port. Normally, the PC will only send untagged frames (frames without specific VLAN ID).

System Requirements

The innovaphone IP phones internal Ethernet switch will not touch the traffic from/to the PC, so the network infrastructure switch must support and be configured for mixed tagged/untagged Ethernet packets on a single port and needs to convert the VLAN id for untagged packets into the designated PC VLAN in order for this scenario to work.

Configuration

You need to configure a VLAN tag on the IP phones (either manually or by DHCP). The phones will send every frame with this configured tag (tagged frames).

The network infrastructure switch needs to be configured as follows

  • inbound tagged packets (arriving at the terminal port) are left "as is". Such packets come from the IP phone and already have the right (Voice) VLAN tag
  • inbound untagged packets are tagged with the designated PC VLAN
  • outbound tagged packets with a PC VLAN tag have the VLAN tag removed (so the PCs will receive untagged frames)
  • all other outbound packets are left unchanged (this includes packets tagged with Voice VLAN ID)

Please note that all IP phones as well as the innovaphone PBXs and gateways have to be in the Voice VLAN (that’s also nice because the innovaphone PBX can then work as DHCP server for the phones only). Even more, all voice servers (such as 3rd party voice mail etc.) receiving voice media streams must be in the same (non-PC!) VLAN so that they can receive the media.

You have then two different networks (VLANs) on one port.

If you configure your whole local network like this, then you can connect your phone to every switch port and you are always in the right VLAN.


The DHCP Server on PC VLAN should be configured with innovaphone DHCP-Option 206 VLAN ID matching the voice VLAN. This way you can connect new phones without configuring the VLAN and don't have problems with DHCP-leases left from phones connected to the PC VLAN before switching them to the Voice VLAN manually. If your PC VLAN DHCP Server sends the innovaphone option 206 the phone will not accept the DHCP Offer and switch to the received VLAN ID.

For more details on using DHCP in this scenario, see Howto:How to use the innovaphone DHCP client

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