Cabletron Systems SmartSwitch manual Interacting with Relay Agents

Chapter 5: DHCP Configuration Guide

6.Define the address pool for ‘scope2’.

dhcp scope2 define pool 10.2.1.40-10.2.1.50

7.Create a superscope ‘super1’ that includes ‘scope1’.

dhcp scope1 attach superscope super1

8.Include ‘scope2’ in the superscope ‘super1’.

dhcp scope2 attach superscope super1

For clients on the secondary subnet, the default gateway is 10.2.1.1, which is also the secondary address for the interface ‘clients’.

Interacting with Relay Agents

For clients that are not directly connected to the DHCP server, a relay agent (typically a router) is needed to communicate between the client and the server. The relay agent is usually only needed during the initial leasing of an IP address. Once the client obtains an IP address and can connect to the network, the renewal of the lease is performed between the client and server without the help of the relay agent.

The default gateway for the client must be capable of reaching the SSR’s DHCP server. The SSR must also be capable of reaching the client’s network. The route must be configured (with static routes, for example) or learned (with RIP or OSPF, for example) so that the DHCP server can reach the client.

The following example shows a simple configuration to support clients across a relay agent.

1.Create an interface ‘clients’ with the primary address 10.1.1.1.

interface create ip clients address-mask 10.1.1.1/16 port et.3.3

2.Define a static route to the 10.5.x.x. subnet using the gateway 10.1.7.10 which tells the DHCP server how to send packets to the client on the 10.5.x.x subnet.

ip add route 10.5.0.0/16 gateway 10.1.7.10

3.Define the network parameters for ‘scope1’ with the default gateway 10.5.1.1 (the relay agent for the client).

dhcp scope1 define parameters address-netmask 10.5.0.0/16 gateway 10.5.1.1 dns-domain acme.com

82 SmartSwitch Router User Reference Manual