CHAPTER
21-1
Catalyst 3750 Switch Software Configuration Guide
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21
Configuring DHCP Features and IP Source Guard
This chapter describes how to configure DHCP snooping and the option-82 data insertion features on the
Catalyst 3750 switch. It also describes how to configure the IP source guard feature. Unless otherwise
noted, the term switch refers to a standalone switch and to a switch stack.
Note For complete syntax and usage information for the commands used in this chapter, refer to the command
reference for this release, and refer to the “DHCP Commands” section in the Cisco IOS IP Command
Reference, Volume 1 of 3: Addressing and Services, Release 12.2.
This chapter consists of these sections:
• Understanding DHCP Features, page 21-1
• Configuring DHCP Features, page 21-7
• Displaying DHCP Snooping Information, page 21-14
• Understanding IP Source Guard, page 21-15
• Configuring IP Source Guard, page 21-16
• Displaying IP Source Guard Information, page 21-19
Understanding DHCP Features
DHCP is widely used in LAN environments to dynamically assign host IP addresses from a centralized
server, which significantly reduces the overhead of administration of IP addresses. DHCP also helps
conserve the limited IP address space because IP addresses no longer need to be permanently assigned
to hosts; only those hosts that are connected to the network consume IP addresses.
The switch supports these DHCP features:
• DHCP Server, page 21-2
• DHCP Relay Agent, page 21-2
• DHCP Snooping, page 21-2
• Option-82 Data Insertion, page 21-3
• DHCP Snooping and Switch Stacks, page 21-6
• Cisco IOS DHCP Server Database, page 21-5
• DHCP Snooping Binding Database, page 21-5