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Allied Telesis AT-8700XL Series manual z AT-8800 series z AT-8600 series z AT-8700XL series

Models: AT-8700XL Series AT-8600 Series Rapier i Series

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Introduction

This document contains the following contents:
Introduction	1
Which products and software version does this information apply to?	2
Related How To Notes	3
DHCP snooping	3
Minimum configuration	3
The database	4
Trusted and non-trusted ports	6
Enabling DHCP snooping	6
Static binding	6
Completely removing the DHCP snooping database	7
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
Configuring the switch for DHCP snooping, filtering and Option 82, when it is
acting as a layer 2 switch	14
Configuring the switch for DHCP snooping, filtering, and Option 82, when it is
acting as a layer 3 BOOTP Relay Agent	17
Troubleshooting	20
No trusted ports configured	20
The DHCP client continually sends requests instead of a discover	21
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:

zAT-8800 series

zAT-8600 series

zAT-8700XL series

zRapier and Rapier i series

Page 2 AlliedWare™ OS How To Note: DHCP Snooping on Rapier-style switches

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Allied Telesis AT-8700XL Series, Rapier i Series manual Which products and software version does this information apply to?

Contents

Introduction AlliedWareTM OSz Rapier and Rapier i series Which products and software version does this information apply to?z AT-8800 series z AT-8600 series z AT-8700XL series DHCP snooping Related How To NotesMinimum configuration DHCP snooping database time-out Database survival across rebootsThe database Verifying the status of snooped usersList of terms Static binding Trusted and non-trusted portsEnabling DHCP snooping DHCP snooping Completely removing the DHCP snooping databaseSo the database is empty DHCP Option DHCP OptionProtocol details Example PacketConfiguring Option AnalysisConfiguring filtering DHCP filteringARP security X To enable DHCP snooping ARP securityDHCP snooping filter show command Resource considerationsExample on a Rapier X If ARP security is enabled, addX or if ARP security is enabled, is Configuration examples X Configure a private VLAN for customersX Add the untagged ports for the customers X Enable DHCP snooping and Option 82 supportX Add the tagged uplink ports to the VLAN X Define the DHCP snooping trusted portsX Create a traffic class for all upstream flow groups X Create a set of QoS classifiersX Define the upstream QoS flow groups create vlan=Customers vid=48 create vlan=Network vid=50 X Configure two VLANs for layer 3 access to the DHCP serverX Add ports to the VLANs add vlan=48 port=1-24 add vlan=50 port=25X Enable DHCP snooping and Option 82 support X For layer 3 support, enable the BOOTP RelayX Define the DHCP snooping trusted port X Configure the switch’s IPX Create a traffic class for all upstream flow groups X Create a set of QoS classifiersX Define the upstream QoS flow groups Troubleshooting No trusted ports configuredDHCPSNProcess 0b47ee6c Error adding entry to DB The DHCP client continually sends requests instead of a discoverMaximum number of leases is exceeded DHCPSNDB Updating entryId 7. FlagsSwitch is dropping ARPs trusted ports TroubleshootingDHCPSNARP 02680e6c ARP to be forwarded, sender validated UntaggedNoneTroubleshooting Displaying log entriesThe show log command is also very useful Appendix 1 ISC DHCP server Appendix 1 ISC DHCP serverif exists agent.circuit-id