
Chapter 7: Configure the DHCP Server
The Avaya 1200 Series IP Deskphones support two basic Dynamic Host Configuration Protocol (DHCP)
mechanisms to provide configuration information to the IP Deskphones. These mechanisms are the
following:
• Normal DHCP
• DHCP VLAN phase
Normal DHCP
The normal DHCP is used to configure standard IP parameters such as IP address, NetMask,
default gateway, and DHCP lease parameters. The message sequence consists of Discover,
Offer, Request, and Acknowledge. The IP Deskphones can also insert an optional phase. To
include an optional phase, the first phase is used to discover and configure the voice VLAN
using a Avaya proprietary method. The second phase then proceeds normally on the
discovered VLAN. If the DHCP VLAN discovery is not used, then there is only a single
phase.
IP Deskphone DHCP VLAN Phase
The DHCP site and vendor specific options contain VLAN information to configure VLANs. The
VLAN parameters are text string embedded in the standard DHCP Vendor and Site Specific
options. You can acquire the VLAN parameters using 802.1ab and IP address parameters
using DHCP.
If the IP Deskphone does not contain VLAN configuration provisioned manually or through
LLDP, the IP Deskphone attempts to determine the VLAN during DHCP VLAN Phase. If the
IP Deskphone does find a VLAN configuration it proceeds to the DHCP Configuration Phase.
If the VLAN Phase (VLAN configured through DHCP) is successful, then the VLAN Phase
finishes with a final DHCP. Also, a release message appears after the completion of the
Configuration Phase.
Following is the procedure to configure the Voice VLAN using DHCP assuming VLAN is not
configured using any other method:
1. The IP Deskphone sends a DHCP request using an untagged (no VLAN) packet
during any of the following scenarios:
• The customer network is configured to handle untagged packets; for example,
retag them to a specific VLAN.
SIP Software for Avaya 1200 Series IP Deskphones-Administration January 2012 83
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