User Guide

OmniAccess SafeGuard OS Administration Guide
196
Chapter 5: Setting Up SafeGuard Switches
inserts a piece of information, called the relay agent information option (option 82), into
any DHCP request packet that is being relayed by the switch. The relay agent information
option is organized as a single DHCP option that contains one or more sub-options. One
of these sub-options is for the incoming circuit in a public circuit access unit. Examples of
a public circuit access unit include RAS's, cable modem termination systems, and ADSL
access units.
The relay agent automatically adds the circuit identifier to the relay agent information
option and forwards it to the DHCP server. When a DHCP reply contains a valid relay
agent option, the option is stripped from the packet before it is relayed to the host.
This sub-option MAY be added by DHCP relay agents which terminate switched or
permanent circuits. It encodes an agent-local identifier of the circuit from which a DHCP
client-to-server packet was received. It is intended for use by agents in relaying DHCP
responses back to the proper circuit. Possible uses of this field include:
■ Router interface number
■ Switching Hub port number
■ Remote Access Server port number
To enable the circuit ID option, use the bootpdhcprelay cidoptmode command in Global
Configuration mode. Use the no version of the command to disable the circuit ID option
mode.
bootpdhcprelay cidoptmode
no bootpdhcprelay cidoptmode
The commands have no parameters or variables.
The following example, enables port information to be inserted into the DHCP request
packet:
(SafeGuardOS) #configure terminal
(SafeGuardOS) (config) #bootpdhcprelay cidoptmode
(SafeGuardOS) (config) #exit
(SafeGuardOS) #
Setting the Maximum Hop Count
By default, a relay agent can hop 4 times. To change the maximum number of hop counts
for a relay agent, use the bootpdhcprelay maxhopcount command. Use the no version of
the command to reinstate the default maximum allowable relay agent hops. These Global
Configuration commands have the following syntax:
bootpdhcprelay maxhopcount hops
no bootpdhcprelay maxhopcount
Syntax Description hops Specifies the maximum number of permitted
hops for a relay request. Valid values are 1 to 16.
The default is 4 hops