Brocade FastIron Ethernet Switch Security Configuration Guide - Manual (Page 344)

DHCP Option 82 sub-options
The Brocade implementation of DHCP Option 82 supports the following sub-options:
• Sub-Option 1 - Circuit ID
• Sub-Option 2 - Remote ID
• Sub-Option 6 - Subscriber ID
These sub-options are described in the following sections.
Sub-option 1 - circuit id
The Circuit ID (CID) identifies the circuit or port from which a DHCP client request was sent. The
FastIron switch uses this information to relay DHCP responses back to the proper circuit, for example,
the port number on which the DHCP client request packet was received.
Brocade FastIron devices support the General CID packet format. This simple format encodes the CID
type, actual information length, VLAN ID, slot number, and port number. This format is compatible with
the format used by other vendors’ devices. The following figure illustrates the general CID packet
format.
FIGURE 28 General CID packet format
Sub-option 2 - Remote ID
The Remote ID (RID) identifies the remote host end of the circuit (the relay agent). Brocade devices
use the MAC address to identify itself as the relay agent. The following figure illustrates the RID packet
format.
FIGURE 29 RID packet format
Sub-option 6 - subscriber id
The Subscriber ID (SID) is a unique identification number that enables an Internet Service Provider to:
• Identify a subscriber
• Assign specific attributes to that subscriber (for example, host IP address, subnet mask, and
domain name server (DNS))
• Trigger accounting
DHCP Option 82 sub-options
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