DHCP Bindings

[bunjiega]

I have been reading the Cisco Press CCNP Switch book and I am partially confused on one of the topics. The topic is DHCP Snooping, I am not grasping how a layer 2 switch can hold the MAC to IP bindings. I could see this on a layer 3 switch, but generally a layer 2 swich just knows the mac-address tables. The book does not specify if it is layer 3 only and it also talks about other topics such as IP Source Guard and Dynamic APR Inspection that also use the database from the DHCP bindings. How would this work, or does this only work on layer 3 switches? Thanks!

[venkata dandu · Accepted solution]

A layer 2 switch does not use the DHCP snooping binding table for switching or routing purposes. The switch creates the table from the DHCP offer packets received by the user end ports and uses the table for securing the network at the access layer switches from APR Spoofing, IP Spoofing and MAC Spoofing attacks.