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.
NOTE:
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.
1
Enable DHCP snooping globally.
CONFIGURATION mode
ip dhcp snooping
2
Specify ports connected to DHCP servers as trusted.
INTERFACE mode
INTERFACE PORT EXTENDER mode
ip dhcp snooping trust
3
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.
1
Enable IPv6 DHCP snooping globally.
CONFIGURATION mode
ipv6 dhcp snooping
2
Specify ports connected to IPv6 DHCP servers as trusted.
INTERFACE mode
ipv6 dhcp snooping trust
3
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
ip dhcp snooping binding mac
Dynamic Host Configuration Protocol (DHCP)
307
Summary of Contents for S4048T-ON
Page 1: ...Dell Configuration Guide for the S4048 ON System 9 11 2 1 ...
Page 148: ...Figure 10 BFD Three Way Handshake State Changes 148 Bidirectional Forwarding Detection BFD ...
Page 251: ...Dell Control Plane Policing CoPP 251 ...
Page 363: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 363 ...
Page 511: ...Figure 64 Inspecting the LAG Configuration Link Aggregation Control Protocol LACP 511 ...
Page 558: ...Figure 84 Configuring Interfaces for MSDP 558 Multicast Source Discovery Protocol MSDP ...
Page 559: ...Figure 85 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 559 ...
Page 564: ...Figure 88 MSDP Default Peer Scenario 2 564 Multicast Source Discovery Protocol MSDP ...
Page 565: ...Figure 89 MSDP Default Peer Scenario 3 Multicast Source Discovery Protocol MSDP 565 ...
Page 841: ...Figure 115 Single and Double Tag TPID Match Service Provider Bridging 841 ...
Page 842: ...Figure 116 Single and Double Tag First byte TPID Match 842 Service Provider Bridging ...