so when the phone say siemens intially boots up does it boot into the default untagged vlan, then does the dhcp server see that its a phone requesting an address, does it then get a different address than the normal pc's and put into the proper vlan.

I have seen in some occasions where you put the phone in the correct vlan first, is this normal ?

It depends on the Vendors implementation. I have never worked with any Siemens IP Phones so I have no idea how they operate. Have a look at their documentation.

Your comment:

'then does the dhcp server see that its a phone requesting an address, does it then get a different address than the normal pc's and put into the proper vlan'

The IP Phone can signal to the DHCP server what it is via DHCP Option 60 (this is the Vendor Class stuff I mentioned). If the DHCP Server is configured appropriately it can provide specific information to that type of client - for example Ericsson IP Phones send 'Ericsson IP-Phone' in DHCP Option 60 in their DHCP Discover & Request packets. The DHCP Server doesn't 'put' the device in the relevant VLAN, this is a function of the IP Phone - i.e. it decides to start 'talking' with the Voice VLAN 802.1q Tag. What usually happens is the IP Phone starts untagged, receives its DHCP Vendor Specific information - usually part of this is the VLAN Tag, it then releases the IP Address and starts again using the VLAN Tag it received.

Not all DHCP Servers support Vendor Classes - in fact other than Windows 2000/2003 I don't know of any others (there must be?).

Andy

so to clarify

phone boots up, gets ip in normal data vlan

dhcp server passes vlan info to phone

phone then reboots

phone then tags packets with new vlan id

is this correct ?

Is this correct? It might be, it depends on the vendor. If its Cisco then no, the Voice VLAN Tag is learned via CDP; unless the Cisco IP Phone didn't see the CDP packet it never appears on the access VLAN. If its Ericsson or Nortel then yes it operates more or less like this - the phones don't actually reboot, they release the IP address in the untagged VLAN and then send a new DHCP request out using the learned Voice VLAN Tag. Mitel IP Phones can use either as they support CDP and also have a DHCP vendor option.

I don't know about other vendors, you should check with the documentation.

Andy

Hello,

for Siemes Phones it looks like this for example.

Untagged Subnet is 192.1.22.0 and tagged (with VLAN ID 20) it is 10.1.22.0.

OptiPoint 410 should get the VLAN ID 20 via VLAN Discovery:

Please make sure that the untagged packets of the first DHCP Discover cycle reach the DHCP server that provides the vendor specific options for the optiPoint. Most likely you will have to use Relay Agents/DHCP Helper.

The options for the 192.1.22.0 subnet have to contain the option 43.

The data format of the option 43 is following:

Option Code for the first encapsulated option:

Always: 01

Length of the first data field:

Always: 0A (10 Byte)

Encapsulated data for option code 1:

Always: 53 69 65 6D 65 6E 73 00 00 00 (Siemens plus 3 Fill bytes)

Option Code for the second encapsulated option:

Always: 02

Length of the first data field:

Always: 04 (4 Bytes)

Encapsulated data for option code 2 (VLAN ID):

Example: for VLAN ID 20: 00 00 00 14

Ending with 5 Padding Bytes and the end option:

Release Note page 9 (of 10) [optiPoint 410 advanced]

Always: 00 00 00 00 00 FF

If this data format for option 43 is not matching or not send by the DHCP server the phone will start with the manual

configured VLAN ID, if Layer 2 QoS is enabled. If Layer 2 QoS is not enabled the phone will start without using a

VLAN ID.

Bye

Jo

Hi there igross

can you confirm the phone first gets a ip address in the data vlan, then it gets passed the options with the new vlan id, then phone requests new ip in voice vlan ?

Hello Carl,

yes it works in this way. Be sure that you have enough free ip addresses in the data vlan. You can speed up the freeing of unused ip addresses in the data vlan by telling the dhcp server to try to ping adresses and set them free is nobody answers.

Bye

Jo

You might try LLDP to set the VVID, if your phone supports it. We are moving our Nortel IP phones over to LLDP and had good luck so far.

what is the lldp ?

Hello,

I tried Siemens Phones with an IP8K with LLDP and had no luck, but I don't now the sw version of the IP8K.

Bye

Jo

Hello Carl,

LLDP means Link Layer Discovery Protocol (LLDP) and LLDP Media Endpoint Discovery (LLDP-MED). This is a standard for CDP.

Its Supported on Cisco Switches starting with 12.2(37) afaik.

Bye

Jo

Use 12.2(44) code as ealier versions had a bug. Configure your phone to support LLDP-MED, and enable LLDP "LLDP RUN".