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xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch CLI Reference Guide
424
DGS-3420-28SC:admin#disable address_binding trap_log
Command: disable address_binding trap_log
Success.
DGS-3420-28SC:admin#
41-13 enable address_binding dhcp_snoop
Description
This command is used to enable the address binding DHCP snooping mode. By default, DHCP
snooping is disabled. If a user enables DHCP snooping, all address binding disabled ports will
function as server ports (the switch will learn IP addresses through server ports (by DHCP OFFER
and DHCP ACK packets)). Note that the DHCP discover packet can not be passed through the
user ports if the ‘forward_dhcppkt’ function is disabled on this port.
The auto-learned IP-MAC-Port binding entry will be mapped to a specific source port based on the
MAC address learning function. This entry will be created as an binding entry for this specific port.
Each entry is associated with a lease time. When the lease time expires, the expired entry will be
removed from this port. The auto-learned binding entry can be moved from one port to another
port if the DHCP snooping function has learned that the MAC address has moved to a different
port.
Consider the case in which a binding entry learned by DHCP snooping conflicts with the statically
configured entry. This means that the binding relation is in conflict. For example, if IP A is binded
with MAC X by static configuration, suppose that the binding entry learned by DHCP snooping is
IP A binded by MAC Y, then there is a conflict. When the DHCP snooping learned entry is binded
with the static configured entry, then the DHCP snooping learned entry will not be created.
Consider the other conflict case, when the DHCP snooping learned a binding entry, and the same
IP-MAC-Port binding pair has been statically configured. If the learned information is consistent
with the statically configured entry, then the auto-learned entry will not be created. If the entry is
statically configured in ARP table, then the auto learned entry will not be created. If the entry is
statically configured on one port and the entry is auto-learned on another port, then the auto-
learned entry will not be created either.
Format
enable address_binding dhcp_snoop {[ipv6 | all]}
Parameters
ipv6 – (Optional) Specifies that the address used is an IPv6 address.
all – (Optional) Specifies that all IP addresses will be used.
Restrictions
Only Administrator, Operator and Power-User level users can issue this command.
Example
To enable the address binding DHCP snooping mode: