3-9
Catalyst 2928 Switch Software Configuration Guide
OL-23389-01
Chapter 3 Assigning the Switch IP Address and Default Gateway
Assigning Switch Information
The default configuration file contains the hostnames-to-IP-address mapping for the switch. The
switch fills its host table with the information in the file and obtains its hostname. If the hostname
is not found in the file, the switch uses the hostname in the DHCP reply. If the hostname is not
specified in the DHCP reply, the switch uses the default
Switch
as its hostname.
After obtaining its hostname from the default configuration file or the DHCP reply, the switch reads
the configuration file that has the same name as its hostname (
hostname
-confg or
hostname
.cfg,
depending on whether network-confg or cisconet.cfg was read earlier) from the TFTP server. If the
cisconet.cfg file is read, the filename of the host is truncated to eight characters.
If the switch cannot read the network-confg, cisconet.cfg, or the hostname file, it reads the
router-confg file. If the switch cannot read the router-confg file, it reads the ciscortr.cfg file.
Note
The switch broadcasts TFTP server requests if the TFTP server is not obtained from the DHCP replies,
if all attempts to read the configuration file through unicast transmissions fail, or if the TFTP server
name cannot be resolved to an IP address.
Example Configuration
shows a sample network for retrieving IP information by using DHCP-based
autoconfiguration.
Figure 3-3
DHCP-Based Autoconfiguration Network Example
shows the configuration of the reserved leases on the DHCP server.
Switch 1
00e0.9f1e.2001
Cisco router
111394
Switch 2
00e0.9f1e.2002
Switch 3
00e0.9f1e.2003
DHCP server
DNS server
TFTP server
(tftpserver)
10.0.0.1
10.0.0.10
10.0.0.2
10.0.0.3
Switch 4
00e0.9f1e.2004
Table 3-2
DHCP Server Configuration
Switch A
Switch B
Switch C
Switch D
Binding key (hardware address)
00e0.9f1e.2001
00e0.9f1e.2002
00e0.9f1e.2003
00e0.9f1e.2004
IP address
10.0.0.21
10.0.0.22
10.0.0.23
10.0.0.24
Subnet mask
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
Router address
10.0.0.10
10.0.0.10
10.0.0.10
10.0.0.10
DNS server address
10.0.0.2
10.0.0.2
10.0.0.2
10.0.0.2
