MNS-BB Software User Guide
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5.3.3 Configuring IP Addressing
1.DHCP/Bootp requests are automatically broadcast on the local network.
(The switch sends one type of request to which either a DHCP or Bootp server can respond.)
2. When a DHCP or Bootp server receives the request, it replies with a previously configured IP
address and subnet mask for the switch. The switch also receives an IP Gateway address if the server
has been configured to provide one. In the case of Bootp, the server must first be configured with an
entry that has the MAC address of the switch. To determine the switch’s MAC address, use CLI
command:
LE2425A#show mac
MAC Address: 00:20:06:25:00:11
Note If you manually configure a gateway on the switch, it will ignore any gateway address received
via DHCP or Bootp.
If the switch is initially configured for DHCP/Bootp operation, or if it is rebooted with this
configuration, it immediately begins sending request packets on the network. If the switch does not
receive a reply to its DHCP/Bootp requests, it continues to periodically send request packets, but with
decreasing frequency. Thus, if a DHCP or Bootp server is not available or accessible to the switch
when DHCP/Bootp is first configured, the switch may not immediately receive the desired
configuration. After verifying that the server has become accessible to the switch, reboot the switch to
re-start the process immediately.
5.3.4 DHCP Operation
A significant difference between a DHCP configuration and a Bootp configuration is that an IP
address assignment from a DHCP server is automatic. Depending on how the DHCP server is
configured, the switch may receive an IP address that is temporarily leased from the DHCP.
Periodically the switch may be required to renew its lease of the IP configuration. Thus, the IP
addressing provided by the server may be different each time the switch reboots or renews its
configuration from the server. However, you can fix the address assignment for the switch by doing
either of the following:
_ Configure the server to issue an “infinite” lease.
_ Using the switch’s MAC address as an identifier, configure the server with a “Reservation” so that
it will always assign the same IP address to the switch.
For more information on either of these procedures, refer to the documentation provided with the
DHCP server.
For DHCP operation:
• The entire scope of DHCP configuration has been updated on the appropriate DHCP server.
• The necessary network connections are in place
• A DHCP server is accessible from the switch
After you reconfigure or reboot the switch while in a network providing DHCP/Bootp service with
DHCP/Bootp enabled, the switch does the following:
_ Receives an IP address,
_ Subnet mask, and
_ Gateway IP address (if configured in the server)
5.3.5 Bootp Operation
When a Bootp server receives a request, it searches its Bootp database for a record entry that matches
the MAC address in the Bootp request from the switch. If a match is found, the configuration data in
the associated database record is returned to the switch. For many UNIX systems, the Bootp database
is contained in the /etc/bootptab file. In contrast to DHCP operation, Bootp configurations are
always the same for a specific receiving device. That is, the Bootp server replies to a request with a
configuration previously stored in the server and designated for the requesting device.
5.3.6 Bootp Database Record Entries
A minimal entry in the Bootp table file /etc/bootptab to update an IP address and subnet mask to the
switch would be similar to this entry:
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