Enabling Dhcp Snooping; Ip Dhcp Snooping; Ip Dhcp Snooping Trust; Ipv6 Dhcp Snooping - Dell S6100 Configuration Manual

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DHCP snooping is supported on Layer 2 and Layer 3 traffic. DHCP snooping on Layer 2 interfaces does require a relay agent.

Binding table entries are deleted when a lease expires or when the relay agent encounters a DHCPRELEASE. Line cards maintain a list of

snooped VLANs. When the binding table is exhausted, DHCP packets are dropped on snooped VLANs, while these packets are forwarded

across non-snooped VLANs. Because DHCP packets are dropped, no new IP address assignments are made. However, DHCPRELEASE

and DHCPDECLINE packets are allowed so that the DHCP snooping table can decrease in size. After the table usage falls below the

maximum limit of 4000 entries, new IP address assignments are allowed.

DHCP server packets are dropped on all not trusted interfaces of a system configured for DHCP snooping. To prevent

these packets from being dropped, configure ip dhcp snooping trust on the server-connected port.

Enabling DHCP Snooping

To enable DHCP snooping, use the following commands.

Enable DHCP snooping globally.

CONFIGURATION mode

Specify ports connected to DHCP servers as trusted.

INTERFACE mode

INTERFACE PORT EXTENDER mode

Enable DHCP snooping on a VLAN.

CONFIGURATION mode

ip dhcp snooping vlan name

Enabling IPv6 DHCP Snooping

To enable IPv6 DHCP snooping, use the following commands.

Enable IPv6 DHCP snooping globally.

CONFIGURATION mode

Specify ports connected to IPv6 DHCP servers as trusted.

INTERFACE mode

Enable IPv6 DHCP snooping on a VLAN or range of VLANs.

CONFIGURATION mode

ipv6 dhcp snooping vlan vlan-id

Adding a Static Entry in the Binding Table

To add a static entry in the binding table, use the following command.

Add a static entry in the binding table.

EXEC Privilege mode

Dynamic Host Configuration Protocol (DHCP)