Cisco Catalyst 4500 Series Configuration Guide

50-6
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
OL-25340-01
Chapter 50 Configuring DHCP Snooping, IP Source Guard, and IPSG for Static Hosts
Configuring DHCP Snooping
Figure 50-3 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.
Figure 50-3 User-Configured Suboption Packet Formats
Configuring DHCP Snooping
When you configure DHCP snooping on your switch, you are enabling the switch to differentiate
untrusted interfaces from trusted interfaces. You must enable DHCP snooping globally before you can
use DHCP snooping on a VLAN. You can enable DHCP snooping independently from other DHCP
features.
These sections describe how to configure DHCP snooping:
• Default Configuration for DHCP Snooping, page 50-7
• Enabling DHCP Snooping, page 50-7
Length Length
Circuit
ID type
Suboption
type
Circuit ID Suboption Frame Format (for user-configured string):
Remote ID Suboption Frame Format (for user-configured string):
Suboption
type
Length Length
Remote
ID type
145774
N1N+2 1
N1N+2 2
ASCII Circuit ID string
1 byte 1 byte 1 byte N bytes (N = 3-63)
ASCII Remote ID string or hostname
N bytes (N = 1-63)
1 byte
1 byte 1 byte 1 byte1 byte

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E