Cisco WS-CBS3032-DEL Software Configuration Manual page 553

Chapter 22 Configuring DHCP Features and IP Source Guard
Remote-ID suboption fields
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In the port field of the circuit ID suboption, the port numbers start at 1. For example, on a switch with
Cisco dual SFP X2 converter modules in the 10-Gigabit Ethernet module slots, port 1 is the internal
Gigabit Ethernet 1/0/1 port, port 2 is the internal Gigabit Ethernet1/0/2 port, and so on. For the external
uplink ports (port 17 to port 20), port 17 is the Gigabit Ethernet 1/0/17 port, port 18 is the Gigabit
Ethernet 1/0/18 port, and so on. Because ports 21, 22, 23, and 24 are small form-factor pluggable (SFP)
modules, port 21 is the Gigabit Ethernet1/0/21 port, port 22 is the Gigabit Ethernet1/0/22 port, and so on.
Figure 22-2
the default suboption configuration is used. For the circuit-ID suboption, the module number
corresponds to the switch number in the stack. The switch uses the packet formats when you globally
enable DHCP snooping and enter the ip dhcp snooping information option global configuration
command.
Figure 22-2
Circuit ID Suboption Frame Format
Suboption
type
1
1 byte
Remote ID Suboption Frame Format
Suboption
type
2
1 byte
Figure 22-3
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.
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
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OL-13270-06
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
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
The circuit-ID type is 1.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Module Port
1 byte 1 byte
MAC address
6 bytes
Understanding DHCP Features
22-5