Dell PowerConnect 5548 User Guide - Page 207

DHCP IPv4 Interface The switch can operate in the following ways: • It can function as a DHCP client that obtains its own IP from a DHCP server, as described in this section • It can function as a DHCP server that allocates IP addresses to other devices, as described in "DHCP Server" on page 290 When the interface is configured as a DHCP client, it keeps requesting an IP address from the DHCP server, until it receives one. It then sends Address Resolution Protocol (ARP) packets to confirm the uniqueness of the IP address. If the ARP response shows that the IP address is in use, the switch sends a DHCPDECLINE message to the DHCP server, and sends another DHCPDISCOVER packet that restarts the process. IP address collisions occur when the same IP address is used in the same IP subnet by more than one device. Address collisions require administrative actions on the DHCP server and/or the devices that collide. Up to 32 interfaces (ports, LAGs, and/or VLAN) on the switch can be configured with a static or dynamic IP address. The IP subnets to which these IP addresses belong are known as directly connected/attached IP subnets. The IP address assignment rules for the switch are as follows: • If the IP address on the switch is changed, the switch issues gratuitous ARP packets to the corresponding VLAN, to check IP address collisions. • When a client must renew its lease, prior to its expiration date, a DHCPREQUEST message is sent. • A specific interface can have either a static IP address or a dynamic IP address, but not both. Dell PowerConnect 55xx Systems User Guide 207