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Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 20 Configuring DHCP Features and IP Source Guard Features
Understanding DHCP Snooping
Figure 20-2 Suboption Packet Formats
Figure 20-3 shows the packet formats for user-configured remote-ID and circuit-ID suboptions The
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.
The values for these fields in the packets change from the default values when you configure the
remote-ID and circuit-ID suboptions:
Circuit-ID suboption fields
The circuit-ID type is 1.
The length values are variable, depending on the length of the string that you configure.
Remote-ID suboption fields
The remote-ID type is 1.
The length values are variable, depending on the length of the string that you configure.
Length Length
Circuit
ID type
Suboption
type
Circuit ID Suboption Frame FormatRemote 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