Nortel Networks BCM50 - Manual (Page 70)

70 Chapter 4 Determining DHCP server configuration and IP address
NN40020-302
If an external DHCP server is present
If an external DHCP is present, then the BCM50 system uses the IP configuration supplied by the
external DHCP server. In this case, the DHCP server on the main unit supplies only IP Phones
with IP configuration information. The DHCP server on the main unit does not supply any other
devices with IP settings. This means that the administrator need not set up the external DHCP
server to supply configuration settings to the IP Phones.
The DHCP server on the main unit must configure a range of IP addresses to supply to the
IP Phones. The DHCP server uses the top 20 percent of a subnet.
For example, if the external DHCP server supplies the IP address 177.218.21.45 (subnet mask is
255.255.255.0) to the BCM50, then the BCM50 DHCP server reserves the range 177.218.21.200
to 177.218.21.254.
You can verify and change this default range using Element Manager.
The administrator must ensure that this range agrees with the network configuration—the external
DHCP server does not use the range.
BCM50a, BCM50ba, BCM50e, and BCM50be main units
(with integrated router)
By default, you configure the BCM50a, BCM50ba, BCM50e, and BCM50be main units with a
dynamic IP address, meaning that these units request an IP configuration from a DHCP server.
Because the integrated router has a DHCP server, this DHCP server responds to the request.
By default, the router LAN IP address is 192.168.1.1, and the IP address assigned to the BCM50
system is the first IP address in the DHCP pool. If the DHCP pool starts at 192.168.1.190, then the
BCM50 is 192.168.1.190 even though the router is 192.168.1.1. Therefore, the BCM50 system
receives the IP address 192.168.1.2 (subnet mask is 255.255.255.0) from the DHCP server on the
integrated router.
The DHCP server on the integrated router supplies the information (primary and secondary TPS
server information, VLAN IDs) to the IP Phones enabling the phones to connect to the BCM50. If
the IP address of the integrated router changes, then the IP address reserved for the BCM50
automatically changes. The DHCP server on the integrated router automatically updates the S1
and S2 IP address.
Warning: The DHCP server on the main unit is enabled by default. If your
network already contains a DHCP server, then disable the DHCP server on the
main unit. For more information about disabling the DHCP server, see the
procedure
To disable the DHCP server on the BCM50a, BCM50e, BCM50ba, and
BCM50be main units on page 71.