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Considerations for IP Phones Supported by a Local Survivable Processor
Issue 9.1 June 2006 193
Considerations for IP Phones Supported by a Local
Survivable Processor
A DHCP server assigns IP addresses to IP endpoints dynamically. Avaya IP phones perform a
DHCP discover request to receive an IP address, as well as receive parameters necessary to
function correctly. These parameters include the location of the call control server, the location
of the TFTP server, as well as the directory on the TFTP server from which the phone receives
its upgrades.
When preparing a DHCP server to work with Avaya IP phones, there is an option that must be
administered to allow the Avaya phone to receive the DHCP offer. This option is
“site-specific-option-number” (sson) 176. Different DHCP servers allow for this administration in
different ways, but the sson option must be mapped to 176. Then the option can be set up to
send the information desired to the Avaya phones for the intended activity.
The sson option sends a string that includes the IP address of the Avaya Call Controller with
which the phone will register (“MCIPADD=www.xxx.yyy.zzz”). In an S8400, S8500, or
S8700-series system, this can be a CLAN address; in an S8400 or S8500, this can also be the
IP address for the server’s port that is enabled for processor ethernet; in an S8300 system, this
is the IP address of the S8300. Multiple addresses can be administered to allow for LSP
failover. The second address in the MCIPADD list may be an IP address for a second CLAN
board or an LSP. If a second CLAN board is used, then the third address must be the LSP, and
any subsequent addresses should be alternate LSPs. Local LSPs should appear first in the list,
with remote LSPs later in the list as possible back ups.
If an IP phone loses its connection to the primary controller, it will try to register with an LSP
associated with its network region (as defined on page 3 of the IP Network Region form).
However, if the phone resets, it looses this information and goes to the DHCP server for a
controller. If the only controller in the MCIPADD list is the primary controller, and if the
connection to the primary controller is down, the phone cannot register. Having an LSP in the
MCIPADD list gives the IP phones an alternate controller in this situation.
Note:
Note: It is strongly recommended that at least one LSP be administered in the
MCIPADD list.
Also included in the sson option string is the “MCPORT=1719”. This is the port the phone will
listen on for signalling traffic to the call controller. Next is the tftp server field. This field indicates
to the phone where it is to receive firmware updates, along with the tftp directory field.
Note:
Note: See 4600 Series IP Telephone LAN Administrator’s Guide, 555-233-507, for
information about IP Telephones.