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Configuring the DHCP relay agent ··························································································································· 54
Overview ········································································································································································· 54
Operation ······························································································································································· 54
DHCP relay agent support for Option 82 ·········································································································· 55
DHCP relay agent configuration task list ····················································································································· 55
Enabling DHCP ······························································································································································ 56
Enabling the DHCP relay agent on an interface ········································································································ 56
Specifying DHCP servers on a relay agent ················································································································· 56
Configuring the DHCP relay agent security functions ································································································ 57
Enabling the DHCP relay agent to record relay entries ···················································································· 57
Enabling periodic refresh of dynamic relay entries ··························································································· 57
Enabling DHCP starvation attack protection ······································································································ 58
Configuring the DHCP relay agent to release an IP address ···················································································· 59
Configuring Option 82 ················································································································································· 59
Setting the DSCP value for DHCP packets sent by the DHCP relay agent ······························································· 60
Displaying and maintaining the DHCP relay agent ··································································································· 60
DHCP relay agent configuration examples ················································································································· 61
DHCP relay agent configuration example ·········································································································· 61
Option 82 configuration example ······················································································································· 62
Troubleshooting DHCP relay agent configuration ······································································································ 62
Symptom ································································································································································· 62
Analysis ·································································································································································· 62
Solution ··································································································································································· 63
Configuring the DHCP client ····································································································································· 64
Enabling the DHCP client on an interface ··················································································································· 64
Configuring a DHCP client ID for an interface ··········································································································· 64
Enabling duplicated address detection ······················································································································· 65
Setting the DSCP value for DHCP packets sent by the DHCP client ········································································· 65
Displaying and maintaining the DHCP client ·············································································································· 66
DHCP client configuration example ····························································································································· 66
Network requirements ··········································································································································· 66
Configuration procedure ······································································································································ 66
Verifying the configuration ··································································································································· 67
Configuring DHCP snooping ····································································································································· 69
Overview ········································································································································································· 69
Application of trusted and untrusted ports ·········································································································· 69
DHCP snooping support for Option 82 ·············································································································· 70
DHCP snooping configuration task list ························································································································ 71
Configuring basic DHCP snooping ······························································································································ 71
Configuring Option 82 ················································································································································· 72
Configuring DHCP snooping entry auto backup ········································································································ 73
Enabling DHCP starvation attack protection ··············································································································· 74
Enabling DHCP-REQUEST attack protection ··············································································································· 75
Setting the maximum number of DHCP snooping entries ·························································································· 75
Configuring DHCP packet rate limit ····························································································································· 76
Displaying and maintaining DHCP snooping ············································································································· 76
DHCP snooping configuration examples ····················································································································· 77
Basic DHCP snooping configuration example ··································································································· 77
Option 82 configuration example ······················································································································· 78
Configuring the BOOTP client ··································································································································· 80
BOOTP application ························································································································································ 80
Obtaining an IP address dynamically ························································································································· 80
Protocols and standards ················································································································································ 80
