MP-1xx SIP User’s Manual 10. BootP/DHCP Support
Version 4.4 175 March 2005
10.2 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., ‘MP-108 FXS’ or ‘MP-
104 FXO’) 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.
Note: 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 (refer to Figure B-1 on page 199).
• Use the RS-232 connector (for detailed information on using the RS-232, refer to Section
9.2
on page 170).
• Contact your System Administrator.
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