Cisco CATALYST 2960

CHAPTER
20-1
Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 15.0(1)SE
OL-26520-01
20
Configuring DHCP and IP Source Guard Features
This chapter describes how to configure DHCP snooping and option-82 data insertion, and the DHCP
server port-based address allocation features on the Catalyst 2960, 2960-S, or 2960-C switch. It also
describes how to configure the IP source guard feature.
Note To use the IP source guard feature, the switch must be running the LAN Base image.
Stacking is supported only Catalyst 2960-S switches.
Note For complete syntax and usage information for the commands used in this chapter, see the command
reference for this release, and see the “DHCP Commands” section in the Cisco IOS IP Command
Reference, Volume 1 of 3: Addressing and Services, Release 12.4 on Cisco.com.
• Understanding DHCP Snooping, page 20-1
• Configuring DHCP Snooping, page 20-7
• Displaying DHCP Snooping Information, page 20-12
• Understanding IP Source Guard, page 20-12
• Configuring IP Source Guard, page 20-14
• Displaying IP Source Guard Information, page 20-20
• Understanding DHCP Server Port-Based Address Allocation, page 20-20
• Configuring DHCP Server Port-Based Address Allocation, page 20-21
• Displaying DHCP Server Port-Based Address Allocation, page 20-24
Understanding DHCP Snooping
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.
• DHCP Server, page 20-2
• DHCP Relay Agent, page 20-2
• DHCP Snooping, page 20-2