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Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
78-6511-05
Chapter 6 Configuring the System
Changing IP Information
• Only the IP address is reserved for the switch and provided in the DHCP
reply. The configuration filename is not provided (two-file read method).
The switch receives its IP address and subnet mask from the DHCP server. It
also receives a DNS server IP address and a TFTP server name. The switch
sends a DNS request to the DNS server, specifying the TFTP server name, to
obtain the TFTP server address.
The switch sends a unicast message to the TFTP server to retrieve the
network-confg or cisconet.cfg default configuration file. (If the
network-confg file cannot be read, the switch reads the cisconet.cfg file.)
The default configuration file contains the host names-to-IP-address mapping
for the switch. The switch fills its host table with the information in the file
and obtains its host name. If the host name is not found in the file, the switch
uses the host name in the DHCP reply. If the host name is not specified in the
DHCP reply, the switch uses the default “Switch” as its host name.
After obtaining its host name from the default configuration file or the DHCP
reply, the switch reads the configuration file that has the same name as its host
name (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 host-name
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 name 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.
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