C
ONFIGURING
DHCP S
NOOPING
7-11
DHCP Snooping Service Provider Mode – Once an IP address is
assigned to the host by a DHCP server, the switch sets this entry to static
mode in the MAC address table, and registers the host as a valid entry in
the DHCP snooping table. (Default: Disabled)
- This function applies to all VDSL ports. When set, it will
automatically convert an address assigned to an attached CPE by a
DHCP server to a static entry in the MAC address table. The MAC
address, IP address, lease time, VLAN identifier, and port identifier
are stored in the DHCP snooping table as a valid entry.
- If the lease time assigned by the DHCP server expires, or the
connection between the switch and CPE is broken for any reason, the
entry will be reset to a dynamic state.
Trust Status – Configures the specified interface as trusted.
(Default:Untrusted)
- A trusted interface is an interface that is configured to receive only
messages from within the network. An untrusted interface is an
interface that is configured to receive messages from outside the
network or firewall.
- When DHCP snooping enabled both globally and on a VLAN,
DHCP packet filtering will be performed on any untrusted ports
within the VLAN.
- When an untrusted port is changed to a trusted port, a ll the dynamic
DHCP snooping bindings associated with this port are removed.
Client Limit – Limits the number of host devices which can be attached
to a VDSL port. (Range: 1-48: Default: 5)
The switch will monitor messages sent from a DHCP server to the
attached hosts. Once the number of addresses assigned by the DHCP
server reaches the client limit for an interface, no additional entries will
be stored in the DHCP snooping table, and any subsequent
acknowledgement packets sent by the DHCP server in respo nse to host
requests will be blocked by the switch.