Dhcp Support; Bootp Support; Upgrading The Vcx V7122 - 3Com VCX V7122 User Manual

DHCP Support

When the gateway is configured to use DHCP (DHCPEnable = 1), it attempts to contact the
enterprise's DHCP server to obtain the networking parameters (IP address, subnet mask,
default gateway, primary/secondary DNS server and SIP server address). These network
parameters have a "time limit". After the time limit expires, the gateway must "renew" its
lease from the DHCP server.
Note that if the DHCP server denies the use of the gateway's current IP address and
specifies a different IP address (according to RFC 1541), the gateway must change its
networking parameters. If this happens while calls are in progress, they are not automatically
rerouted to the new network address (since this function is beyond the scope of a VoIP
gateway). Therefore, administrators are advised to configure DHCP servers to allow renewal
of IP addresses.
Note: If the gateway's network cable is disconnected and reconnected, a DHCP renewal is
performed (to verify that the gateway is still connected to the same network).
When DHCP is enabled, the gateway also includes its product name (e.g., 'VCX V7122') in
the DHCP 'option 60' Vendor Class Identifier. The DHCP server can use this product name
to assign an IP address accordingly.
Note: After power-up, the gateway issues two DHCP requests. Only in the second request,
the DHCP 'option 60' is contained. If the gateway is reset from the Web/SNMP, only a single
DHCP request containing 'option 60' is sent.
If DHCP procedure is used, the new gateway IP address, allocated by the DHCP server,
must be detected.
If, during operation, the IP address of the gateway is changed as a result of a
DHCP renewal, the gateway is automatically reset.
To detect the gateway's IP address, follow one of the procedures below:
Starting with Bootload software version 1.92, the gateway can use host name in the
DHCP request. The host name is set to acl_nnnnn, where nnnnn stands for the
gateway's serial number (the serial number is equal to the last 6 digits of the MAC
address converted from Hex to decimal). If the DHCP Server registers this host name to
a DNS server, the user can access the gateway (through a Web browser) using a URL of
http://acl_<serial number> (instead of using the gateway's IP address). For example, if
the gateway's MAC address is 00908f010280, the DNS name is acl_66176.
After physically resetting the gateway its IP address is displayed in the 'Client Info'
column in the BootP/TFTP configuration utility (see
Contact your System Administrator.

BootP Support

Upgrading the VCX V7122

When upgrading the VCX V7122 (loading new software onto the gateway) using the
BootP/TFTP configuration utility:
3Com VCX V7122 SIP VoIP Gateway User Manual
Figure 65 on page 195).
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