25
IP Source Guard
25.1 Overview
Use IP source guard to filter unauthorized DHCP and ARP packets in your network.
IP source guard uses a binding table to distinguish between authorized and unauthorized DHCP and ARP packets in your network. A binding contains these key attributes:
•MAC address
•VLAN ID
•IP address
•Port number
When the Switch receives a DHCP or ARP packet, it looks up the appropriate MAC address, VLAN ID, IP address, and port number in the binding table. If there is a binding, the Switch forwards the packet. If there is not a binding, the Switch discards the packet.
25.1.1What You Can Do
•Use the IP Source Guard screen (Section 25.2 on page 222) to look at the current bindings for DHCP snooping and ARP inspection.
•Use the IP Source Guard Static Binding screen (Section 25.3 on page 223) to manage static bindings for DHCP snooping and ARP inspection.
•Use the DHCP Snooping screen (Section 25.4 on page 225) to look at various statistics about the DHCP snooping database.
•Use this DHCP Snooping Configure screen (Section 25.5 on page 228) to enable DHCP snooping on the Switch (not on specific VLAN), specify the VLAN where the default DHCP server is located, and configure the DHCP snooping database.
•Use the DHCP Snooping Port Configure screen (Section 25.5.1 on page 230) to specify whether ports are trusted or untrusted ports for DHCP snooping.
•Use the DHCP VLAN Configure screen (Section 25.5.2 on page 231) to enable DHCP snooping on each VLAN and to specify whether or not the Switch adds DHCP relay agent option 82 information to DHCP requests that the Switch relays to a DHCP server for each VLAN.
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