beautypg.com

Configuring ip dhcp relay, Dhcp protocol, Ip dhcp relay function – Brocade Network OS Administrator’s Guide v4.1.1 User Manual

Page 649: Dhcp protocol ip dhcp relay function

background image

Configuring IP DHCP Relay

DHCP protocol.............................................................................................................. 649

IP DHCP Relay function................................................................................................649

Brocade IP DHCP Relay overview................................................................................650

Configuring IP DHCP Relay.......................................................................................... 651

Displaying IP DHCP Relay addresses for an interface................................................. 654

Displaying IP DHCP Relay addresses on specific switches......................................... 655

Displaying IP DHCP Relay statistics............................................................................. 657

Clearing IP DHCP Relay statistics................................................................................ 658

VRF support.................................................................................................................. 658

High availability support................................................................................................ 660

DHCP protocol

Dynamic Host Configuration Protocol (DHCP) is an IP network protocol that provides network
configuration data, such as IP addresses, default routes, DNS server addresses, access control, QoS
policies, and security policies stored in DHCP server databases to DHCP clients upon request.

You can enable DHCP service on VDX switches so that they can automatically obtain an Ethernet IP
address, prefix length, and default gateway address from the DHCP server. Refer to

Configuring an

IPv4 address with DHCP

on page 68 for more information.

IP DHCP Relay function

DHCP relays are an important feature for large networks as they allow communication between DHCP
servers and clients located on different subnets.

In small networks with only one IP subnet, DHCP clients can communicate directly with DHCP servers.
Clients located on a different subnet than the DHCP server cannot communicate with that server
without obtaining an IP address with appropriate routing information.

By installing a DHCP relay agent on different subnets in a large network, broadcast DHCP packets can
be forwarded from a DHCP client to locate a DHCP server on a remote subnet. The relay agent’s IP
address is stored in the gateway IP address (GIADDR) field of the DHCP packet, The DHCP server
uses the GIADDR field to find the subnet where the relay agent received the broadcast, and then
assigns IP addresses to that subnet. The DHCP server replies to the client with a unicast message to
the GIADDR address and the relay agent will forward the response to the local network.

Network OS Administrator’s Guide

649

53-1003225-04