Cisco Catalyst 4500 Series Software Configuration Manual page 1587

Chapter 60 Configuring DHCP Snooping, IP Source Guard, and IPSG for Static Hosts
In the default suboption configuration, when the described sequence of events occurs, the values in these
fields in
• Circuit ID suboption fields
–
–
–
–
Remote ID suboption fields
•
–
–
–
–
Figure 60-2
default suboption configuration is used. For the circuit ID suboption, the module number corresponds to
the switch module number. The switch uses the packet formats when you globally enable DHCP
snooping and enter the ip dhcp snooping information option global configuration command.
Figure 60-2
Circuit ID Suboption Frame Format
Suboption
type
1
1 byte
Remote ID Suboption Frame Format
Suboption
type
2
1 byte
Figure 60-3
switch uses these packet formats when DHCP snooping is globally enabled and when the ip dhcp
snooping information option format remote-id global configuration command and the ip dhcp
snooping vlan information option format-type circuit-id string interface configuration command are
entered.
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Figure 60-2 do not change:
Suboption type
Length of the suboption type
Circuit ID type
Length of the circuit ID type
Suboption type
Length of the suboption type
Remote ID type
Length of the remote ID type
shows the packet formats for the remote ID suboption and the circuit ID suboption when the
Suboption Packet Formats
Circuit
ID type
Length Length
6 0 4 VLAN
1 byte 1 byte 1 byte 2 bytes
Remote
ID type
Length Length
8 0 6
1 byte 1 byte 1 byte
shows the packet formats for user-configured remote ID and circuit ID suboptions. The
Module Port
1 byte 1 byte
MAC address
6 bytes
About DHCP Snooping
60-5