CLI Reference Guide-R04

Chapter 9 | General Security Measures
DHCPv6 Snooping
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◆ If DHCPv6 snooping is globally disabled, all dynamic bindings are removed
from the binding table.
◆ Additional considerations when the switch itself is a DHCPv6 client – The port(s)
through which the switch submits a client request to the DHCPv6 server must
be configured as trusted (using the ipv6 dhcp snooping trust command). Note
that the switch will not add a dynamic entry for itself to the binding table when
it receives an ACK message from a DHCPv6 server. Also, when the switch sends
out DHCPv6 client packets for itself, no filtering takes place. However, when the
switch receives any messages from a DHCPv6 server, any packets received from
untrusted ports are dropped.
Example
This example enables DHCPv6 snooping globally for the switch.
Console(config)#ipv6 dhcp snooping
Console(config)#
Related Commands
ipv6 dhcp snooping vlan (345)
ipv6 dhcp snooping trust (346)
ipv6 dhcp snooping
option remote-id
This command enables the insertion of remote-id option 37 information into
DHCPv6 client messages. Remote-id option information such as the port attached
to the client, DUID, and VLAN ID is used by the DHCPv6 server to assign
preassigned configuration data specific to the DHCPv6 client. Use the no form of
the command to disable this function.
Syntax
[no] ipv6 dhcp snooping option remote-id
Default Setting
Disabled
Command Mode
Global Configuration
Command Usage
◆ DHCPv6 provides a relay mechanism for sending information about the switch
and its DHCPv6 clients to the DHCPv6 server. Known as DHCPv6 Option 37, it
allows compatible DHCPv6 servers to use the information when assigning IP
addresses, or to set other services or policies for clients.
◆ When DHCPv6 Snooping Information Option 37 is enabled, the requesting
client (or an intermediate relay agent that has used the information fields to
describe itself) can be identified in the DHCPv6 request packets forwarded by
the switch and in reply packets sent back from the DHCPv6 server.