Configuration Guide User guide

1938 FastIron Configuration Guide
53-1002494-02
DHCP relay agent information
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. Figure 215 illustrates the general CID
packet format.
FIGURE 215 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. Figure 216 illustrates the RID packet
format.
FIGURE 216 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
Figure 217 illustrates the SID packet format.
FIGURE 217 SID packet format
The second byte (N in Figure 217) is the length of the ASCII string that follows. The FastIron switch
supports up to 50 ASCII characters.
1 Byte 2 Bytes
1 6 0 4 VLAN ID Slot ID Port
1 Byte
2806
MAC Address
1 Byte
6 N ASCII String 1.....N