3com WXR100 3CRWXR10095A Manual De Usuario

The DHCP client is enabled by default on an unconfigured WXR100 when 
the factory reset switch is pressed and held during power on. The DHCP 
client is disabled by default on all other switch models, and is disabled on 
a WXR100 if the switch is already configured or the factory reset switch is 
not pressed and held during power on.

You can enable the DHCP client on one VLAN only. 

MSS also has a configurable DHCP server. (See “Configuring the DHCP 
Server” on page 665.) You can configure a DHCP client and DHCP server 
on the same VLAN, but only the client or the server can be enabled. The 
DHCP client and DHCP server cannot both be enabled on the same VLAN 
at the same time.

MSS compares the IP parameter values already configured 

on the switch with the values received from the DHCP server, and resolves 
any conflicts as follows:

„

IP address—If the VLAN also has a statically configured IP address, 
MSS uses an address from the DHCP server instead of the statically 
configured address. 

MSS sends an ARP for the IP address offered by the DHCP server to 
verify that the address is not already in use. 

„

If the address is not in use, MSS configures the VLAN that has the 
DHCP client enabled with the IP address received from the DHCP 
server. MSS then configures the other values as follows:

„

Default router—MSS adds a default route for the gateway, with 
a metric of 10. 

„

DNS domain name and DNS server IP address—If the default 
domain name and DNS server IP address are already configured 
on the switch, and DNS is enabled, the configured values are 
used. Otherwise, the values received from the DHCP server are 
used.

„

If the address offered by the DHCP server is already in use, MSS 
sends a DHCP Decline message to the server and generates a log 
message.

„

If the address is in a subnet that is already configured on another 
VLAN on the switch, MSS sends a DHCP Decline message to the 
server and generates a log message.