Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide

16-5
Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide
380261-003
Chapter 16 Configuring DHCP Features
Configuring DHCP Features
In the port field of the circuit ID suboption, the port numbers start at 1. For example, on a CGESM
switch, which has 24 ports, port 1 is the Gigabit Ethernet 0/1 port, port 2 is the Gigabit Ethernet 0/2 port,
port 3 is the Gigabit Ethernet 0/3 port, and so on. Because ports 19, 20, 21, and 22 are small form-factor
pluggable (SFP) modules, port 19 is the SFP module slot 0/1, port 20 is the SFP module slot 0/2, port
21 is the SFP module slot 0/3 and port 22 is the SFP module slot 0/4.
Figure 16-2 shows the packet formats for the remote-ID suboption and the circuit-ID suboption The
switch uses the packet formats when you globally enable DHCP snooping and enter the ip dhcp
snooping information option global configuration command.
Figure 16-2 Suboption Packet Formats
Configuring DHCP Features
These sections contain this configuration information:
• Default DHCP Configuration, page 16-5
• DHCP Snooping Configuration Guidelines, page 16-6
• Configuring the DHCP Relay Agent, page 16-7
• Enabling DHCP Snooping and Option 82, page 16-7
Default DHCP Configuration
Table 16-1 shows the default DHCP configuration.
Length Length
Circuit
ID type
Suboption
type
Circuit ID Suboption Frame Format
Remote ID Suboption Frame Format
6 bytes
MAC address
1 byte 1 byte 1 byte
Suboption
type
1 byte
Length Length
Remote
ID type
1 byte 1 byte 1 byte1 byte
116300
4061
6082
Module Port
1 byte 1 byte2 bytes
VLAN