Understanding Dhcp Snooping - Cisco Catalyst 2975 Software Configuration Manual

Configuring DHCP Features 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 2975 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.
For complete syntax and usage information for the commands used in this chapter, see the command
Note
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 12.2 from the Cisco.com page under
Documentation > Cisco IOS Software > 12.2 Mainline > Command References.
This chapter consists of these sections:
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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.
OL-19720-02
Understanding DHCP Snooping, page 20-1
Configuring DHCP Snooping, page 20-9
Displaying DHCP Snooping Information, page 20-14
Understanding IP Source Guard, page 20-15
Configuring IP Source Guard, page 20-17
Displaying IP Source Guard Information, page 20-22
Understanding DHCP Server Port-Based Address Allocation, page 20-23
Configuring DHCP Server Port-Based Address Allocation, page 20-23
Displaying DHCP Server Port-Based Address Allocation, page 20-26
C H A P T E R
Catalyst 2975 Switch Software Configuration Guide
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