Cisco Systems 3130 User Manual
3-7
Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
OL-13270-01
Chapter 3 Assigning the Switch IP Address and Default Gateway
Assigning Switch Information
Configuring the Relay Device
You must configure a relay device, also referred to as a relay agent, when a switch sends broadcast
packets that require a response from a host on a different LAN. Examples of broadcast packets that the
switch might send are DHCP, DNS, and in some cases, TFTP packets. You must configure this relay
device to forward received broadcast packets on an interface to the destination host.
packets that require a response from a host on a different LAN. Examples of broadcast packets that the
switch might send are DHCP, DNS, and in some cases, TFTP packets. You must configure this relay
device to forward received broadcast packets on an interface to the destination host.
If the relay device is a Cisco router, enable IP routing (ip routing global configuration command), and
configure helper addresses by using the ip helper-address interface configuration command.
configure helper addresses by using the ip helper-address interface configuration command.
For example, in
, configure the router interfaces as follows:
On interface 10.0.0.2:
router(config-if)# ip helper-address 20.0.0.2
router(config-if)# ip helper-address 20.0.0.3
router(config-if)# ip helper-address 20.0.0.4
On interface 20.0.0.1
router(config-if)# ip helper-address 10.0.0.1
Note
If the switch is acting as the relay device, configure the interface as a routed port. For more information,
see the
see the
and the
Figure 3-2
Relay Device Used in Autoconfiguration
Obtaining Configuration Files
Depending on the availability of the IP address and the configuration filename in the DHCP reserved
lease, the switch obtains its configuration information in these ways:
lease, the switch obtains its configuration information in these ways:
•
The IP address and the configuration filename is reserved for the switch and provided in the DHCP
reply (one-file read method).
reply (one-file read method).
The switch receives its IP address, subnet mask, TFTP server address, and the configuration
filename from the DHCP server. The switch sends a unicast message to the TFTP server to retrieve
the named configuration file from the base directory of the server and upon receipt, it completes its
boot up process.
filename from the DHCP server. The switch sends a unicast message to the TFTP server to retrieve
the named configuration file from the base directory of the server and upon receipt, it completes its
boot up process.
Switch
(DHCP client)
Cisco router
(Relay)
49068
DHCP server
TFTP server
DNS server
20.0.0.2
20.0.0.3
20.0.0.1
10.0.0.2
10.0.0.1
20.0.0.4