3Com VCX V7000, Installation Manual

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A
C
ONFIGURING
O
PTION
184
ON A
W
INDOWS
2000 DHCP S
ERVER
Overview
RFC 2132 (DHCP Options and BOOTP Vendor Extensions) allows for
vendor-specific extensions to the DHCP protocol. It defines that option
codes in the range 128 through 254 are set aside for vendor-specific
extensions.
3Com telephones can receive their IP configuration from a DHCP server.
However, 3Com telephones need configuration information that is not
part of a standard DHCP response. You can use DHCP option 184 to
specify this extended information:
■
NCP IP Address — Each telephone must receive a download of
operating settings from the VCX Downloader task, which typically
resides on the VCX Call Processing Server.
■
Alternate Server IP Address — Specifies a second location from
which a telephone can receive its download. Typically, this is the IP
address of the Secondary VCX Call Processing Server in a dual-server
configuration.
■
Voice VLAN Configuration — If you configure any of your 3Com
telephones or your VCX system on Virtual LANs, you can configure
your DHCP server to specify VLAN ID numbers for each scope. You can
also enable and disable VLAN operation for each DHCP scope.
■
Fail-Over Call Route Point — You can define a single fail-over route
point (IP address) and an associated dial string for SIP devices such as
telephones to use.
If a failure occurs on the Primary VCX Call Processing Server, the
telephone switches to the Secondary VCX Call Processing Server. If
both are unavailable, the telephone switches to peer-to-peer SIP
operation and attempts to connect to the IP address of the fail-over
route point. The dial string controls the types of calls that can be made
while the telephone is in peer-to-peer mode.