This document contains the following contents:
Introduction .............................................................................................................................................. 1
Related How To Notes ................................................................................................................... 3
DHCP snooping ....................................................................................................................................... 3
Minimum configuration ................................................................................................................... 3
The database ..................................................................................................................................... 4
Enabling DHCP snooping ............................................................................................................... 6
Static binding ..................................................................................................................................... 6
DHCP Option 82 .................................................................................................................................... 8
Protocol details ................................................................................................................................. 9
Configuring Option 82 .................................................................................................................. 10
DHCP filtering ........................................................................................................................................ 11
Configuring filtering ....................................................................................................................... 11
ARP security .................................................................................................................................... 12
Resource considerations .............................................................................................................. 12
Configuration examples ....................................................................................................................... 14
Troubleshooting ..................................................................................................................................... 20
Switch is dropping ARPs ............................................................................................................... 22
Displaying log entries .................................................................................................................... 24
Appendix 1: ISC DHCP server .......................................................................................................... 25
Which products and software version does this
information apply to?
The information provided in this document applies to the following switches, running
AlliedWare version 2.7.6 and above:
AT-8800 series
AT-8600 series
AT-8700XL series
Rapier and Rapier i series
Page 2 | AlliedWare™ OS How To Note: DHCP Snooping on Rapier-style switches
acting as a layer 2 switch ....................................................................................................... 14
Introduction