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4-3
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 4 Assigning the Switch IP Address and Default Gateway
Assigning Switch Information
Default Switch Information
shows the default switch information.
Understanding DHCP-Based Autoconfiguration
The DHCP provides configuration information to Internet hosts and internetworking devices. This
protocol consists of two components: one for delivering configuration parameters from a DHCP server
to a device and a mechanism for allocating network addresses to devices. DHCP is built on a
client-server model, in which designated DHCP servers allocate network addresses and deliver
configuration parameters to dynamically configured devices. The switch can act as both a DHCP client
and a DHCP server.
During DHCP-based autoconfiguration, your switch (DHCP client) is automatically configured at
startup with IP address information and a configuration file.
With DHCP-based autoconfiguration, no DHCP client-side configuration is needed on your switch.
However, you need to configure the DHCP server or the DHCP server feature on your switch for various
lease options associated with IP addresses. If you are using DHCP to relay the configuration file location
on the network, you might also need to configure a Trivial File Transfer Protocol (TFTP) server and a
Domain Name System (DNS) server.
The DHCP server or the DHCP server feature running on your switch can be on the same LAN or on a
different LAN than the switch. If the DHCP server is running on a different LAN, you should configure
a DHCP relay. A relay device forwards broadcast traffic between two directly connected LANs. A router
does not forward broadcast packets, but it forwards packets based on the destination IP address in the
received packet.
DHCP-based autoconfiguration replaces the BOOTP client functionality on your switch.
DHCP Client Request Process
When you boot your switch, the switch automatically requests configuration information from a DHCP
server only if a configuration file is not present on the switch.
DHCP autoconfiguration does not occur under these conditions:
•
When a configuration file is present and the service config global configuration command is
disabled on the switch.
Table 4-1
Default Switch Information
Feature
Default Setting
IP address and subnet mask
No IP address or subnet mask are defined.
Default gateway
No default gateway is defined.
Enable secret password
No password is defined.
Host name
The factory-assigned default host name is Switch.
Telnet password
No password is defined.
Cluster command switch functionality
Disabled.
Cluster name
No cluster name is defined.