CLI Reference Guide-R02

Chapter 9 | General Security Measures
DHCPv4 Snooping
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The ip dhcp snooping information option circuit-id command can be
used to modify the default settings described above.
◆ The format for TR101 option 82 is: “<IP> eth <SID>/<PORT>[:<VLAN>]”. Note
that the SID (Switch ID) is always 0. By default the PVID is added to the end of
the TR101 field for untagged packets. For tagged packets, the VLAN ID is always
added.
Example
This example enables the use of sub-type and sub-length fields for the
circuit-ID (CID) and remote-ID (RID).
Console(config)#no ip dhcp snooping information option encode no-subtype
Console(config)#
ip dhcp snooping
information option
remote-id
This command sets the remote ID to the switch’s IP address, MAC address, arbitrary
string, TR-101 compliant node identifier, or removes VLAN ID from the end of the
TR101 field. Use the no form to restore the default setting.
Syntax
ip dhcp snooping information option remote-id
{ip-address [encode {ascii | hex}] |
mac-address [encode {ascii | hex}] | string string [sub-option port-
description [delimiter delimiter]] |
tr101 {node-identifier {ip | sysname} | no-vlan-field }}
no ip dhcp snooping information option remote-id
[ip-address encode] | [mac-address encode] | [string sub-option port-
description delimiter] | [tr101 no-vlan-field]