[Asterisk-Users] Push VLAN to Polycom via DHCP

[Matt Darnell]

On Mon, 28 Mar 2005 14:29:15 -0600, Jerry <jjones at quiddesign.com> wrote:
> 
> On Mar 27, 2005, at 12:10 AM, Matt Darnell wrote:
> 
> >>> Has anyone been succesful pushing a VLAN setting to a Polycom phone
> >>> via DHCP?
> >
> >>  Chicken or the egg!  How can the Polycom reach the proper DHCP server
> >> if it is not on the correct VLAN?  That's why Ciscos and Polycoms
> >> support CDP, so the CDP-capable switch can supply the correct voice
> >> VLAN.
> >
> > I 'assumed' the phone would reboot with the new VLAN setting and get a
> > new IP address from the DHCP server on the phone VLAN - there would be
> > two DHCP servers.
> >
> > I can't think of any other way to make it work with DHCP.  If it isn't
> > designed to work that way, why would they put the option in the DHCP
> > section.
> >
> > -Matt
> 
> I had always understood that they only supported VLAN discovery via
> CDP. But reading the 1.4 admin guide it says this...
> 
> VLAN ID
> See 2.2.1.2.2
> DHCP Menu
> on page 7
> Special Case: Cisco Discovery Protocol (CDP)a overrides
> Local FLASH which overrides DHCP VLAN
> Discovery.
> a. Can be obtained from a connected Ethernet switch if the switch
> supports CDP.
> 
> This seems to imply that DHCP can be used to spec a VLAN.


Looks like logic has let us down again.

After talking with Polycom it doens't do what it reads.  Here is the
quote from the manual:

********
VLAN Discovery

Disabled - No VLAN discovery via DHCP.

Fixed - Use predefined DHCP private option values of 128, 144, 157 and
191. If this is used, the VLAN ID Option field will be ignored.

Custom - Use the number specified in the VLAN ID Option field as the
DHCP private option value. VLAN ID Option 128 through 254 (Cannot be
the same as Boot Server Option)

The DHCP private option value (when VLAN Discovery is set to Custom).
Default is 129.
*******

I can't see how that could mean anything else.

Maybe I should sleep on it.

-M