VoIP Mailing List Archives

[ken at jots.org]

Hi, all. I see that the Polycom SoundPoint IP 330 supports VLAN... but I
don't quite see how that works. Do you point a non-VLAN'd segment at it
(akin to when you uplink a VLAN_enabled switch), and have the phone
implement the VLAN? Or...? *puzzled*

Thanks much,

-Ken

[jra at baylink.com]

On Tue, Mar 11, 2008 at 04:48:19PM -0400, Ken D'Ambrosio wrote:

[jsneerin at gmail.com]

The 330/550/650 phones have a built-in 2-port switch that speaks
802.1q. Usual use of this is to send two VLANs down the wire. The
phone is configured to use one, and the phone transparently passes the
other to the phone's PC port. On Cisco, this would be a trunk port
with two VLANs, one for the phone and one for the PC (the latter
usually being the default VLAN). On HP ProCurve, you assign one tagged
and one untagged VLAN to the phone.

The VLAN used by the phone can be configured in several ways:

1. Hard-code it on the phone. Not recommended if you have lots of phones.
2. Auto-discovery using CDP. Requires Cisco or older HP switches.
3. Auto-discovery using DHCP. Disabled by default in SIP 2.1.x.

We use the third option. The phone first does DHCP on the default VLAN
(since it does not yet know which VLAN to use). The DHCP server sends
back the VLAN to use, which cause the phone to send a DHCP release,
reconfigure itself for the new VLAN, and do DHCP again on the new
VLAN. We use this method because we have newer HP switches that have
removed CDP support in favor of LLDP, which Polycom does not (yet?)
support.

-James
On 3/11/08, Ken D'Ambrosio <ken at jots.org> wrote:

[noahisaacmiller at gma...]

Hi James -