Dell POWEREDGE M1000E - Manual (Page 547)

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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-13270-03
Chapter 22 Configuring DHCP Features and IP Source Guard
Understanding DHCP Features
• Remote-ID suboption fields
– Suboption type
– Length of the suboption type
– Remote-ID type
– Length of the remote-ID type
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 shows the packet formats for the remote-ID suboption and the circuit-ID suboption when
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 Suboption Packet Formats
Figure 22-3 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.
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 byte 1 byte
116300
4 0 6 1
6 0 8 2
Module Port
1 byte 1 byte 2 bytes
VLAN