Nortel 1120E Administration Manual page 62

62 Configure the DHCP server
After multiple VLAN IDs are returned from the DHCP server, the IP Phone
1120E tries to connect to each of the VLANs, following the order in which
VLAN IDs are specified in the DHCP option.
The format of the field for DHCP VLAN Auto Discovery is: Type, length, and
data, described in the following sections.
Type (1 octet)
To avoid the possibility of option types already being used by different
vendors, there are fourteen options types supported by the telephone. They
are: 128, 131, 144, 157, 188, 191, 205, 219, 223, 232, 247, 251, 247, and
251. Select one value from the type byte list for the DHCPOFFER response.
Nortel recommends using 232, 247, or 251. DHCP option numbers less
than 224 are reclaimed by the IETF (RFC 3942). Future changes in the
DHCP protocol can force the telephone to stop sending these option
requests. Currently, IP Phone 1120E with SIP Firmware does support the
remaining listed options to maintain backward compatibility.
Length (1 octet)
The Length value is variable. Count only the number of octets in the data
field.
Data (variable number of octets)
ASCII based format: VLAN-A:XXX+YYY+ZZZ. where, VLAN– A: uniquely
identifies this as the Nortel DHCP VLAN discovery request. Each VLAN ID
is followed by a plus (+) sign if there are more VLAN IDs or a period (.) to
terminate the string.
There are a maximum of 10 VLAN IDs that can be configured in the current
version.
Once the IP Phone 1120E with SIP Firmware receives the DHCP offer
containing the site-specific Voice VLAN option, the next DHCPDISCOVERY
message is tagged with the Voice VLAN ID.
Copyright © 2008, Nortel Networks
.
SIP Firmware Release 1.1 for IP Phone 1120E Administration
NN43112-300 02.03 Standard
27 May 2008