Version 7.2 221 Mediant 1000B Gateway & E-SBC
User's Manual 15. Services
15 Services
This section describes configuration for various supported services.
15.1 DHCP Server Functionality
The device can serve as a Dynamic Host Configuration Protocol (DHCP) server that
assigns and manages IP addresses from a user-defined address pool for DHCP clients.
The DHCP server can also be configured to supply additional information to the requesting
client such as the IP address of the TFTP server, DNS server, NTP server, and default
router (gateway). The DHCP server functionality complies with IETF RFC 2131 and RFC
2132.
The DHCP server can service up to 600 DHCP clients. The DHCP clients are typically IP
phones that are connected to the device's LAN port.
The DHCP server is activated when you configure a valid entry in the DHCP Servers table
(see ''Configuring the DHCP Server'' on page 221) and associate it with an active IP
network interface (listed in the IP Interfaces table). When an IP phone on the LAN requests
an IP address, the DHCP server allocates one from the address pool. In scenarios of
duplicated IP addresses on the LAN (i.e., an unauthorized network device using one of the
IP addresses of the DHCP address pool), the DHCP server detects this condition using an
Address Resolution Protocol (ARP) request and temporarily blacklists the duplicated
address.
You can also configure the DHCP server to respond only to DHCPDiscover requests from
DHCP clients that contain a specific value for Option 60 (Vendor Class Identification). For
more information, see ''Configuring the Vendor Class Identifier'' on page 226.
15.1.1 Configuring the DHCP Server
The DHCP Servers table lets you configure the device's DHCP server. The DHCP Server
table configures the DHCP server implementation. This includes configuring the DHCP IP
address pool from where IP addresses are allocated to requesting DHCP clients, as well
as configuring other information such as IP addresses of the DNS server, NTP server,
default router (gateway), and SIP proxy server. The DHCP server sends the information in
DHCP Options. The table below lists the DHCP Options that the DHCP server sends to the
DHCP client and which are configurable in the DHCP Servers table.
Table 15-1: Configurable DHCP Options in DHCP Servers Table
DHCP Option Code DHCP Option Name
Option 53 DHCP Message Type
Option 54 DHCP Server Identifier
Option 51 IP Address Lease Time
Option 1 Subnet Mask
Option 3 Router
Option 6 Domain Name Server
Option 44 NetBIOS Name Server
Option 46 NetBIOS Node Type
Option 42 Network Time Protocol Server
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