User`s manual

Mediant 2000 & TP-1610 & TP-260
SIP User's Manual 204 Document #: LTRT-68805
7.2 Using DHCP
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 two SIP server addresses). 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., ‘Mediant 2000’)
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 performs two distinct DHCP sequences. Only in the
second sequence, DHCP ‘option 60’ is contained. If the gateway is reset from the
Web/SNMP, only a single DHCP sequence containing ‘option 60’ is sent.
If DHCP procedure is used, the new gateway IP address, allocated by the DHCP server,
must be detected.
Note: If, during operation, the IP address of the gateway is changed as a result of
a DHCP renewal, the gateway is automatically reset.
¾ To detect the gateway’s IP address, follow one of the procedures
below:
 Starting with Boot version 1.92, the gateway can use a 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 (refer to Figure D-1 on page 355).
 Contact your System Administrator.