User`s manual

NPort S8000 Series Switch Featured Functions
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to a DHCP server. Servers can recognize the Relay Agent Information option and use the information to
implement IP addresses to Clients.
When Option 82 is enabled on the switch, a subscriber device is identified by the switch port through which it
connects to the network (in addition to its MAC address). Multiple hosts on the subscriber LAN can be connected
to the same port on the access switch and are uniquely identified.
The Option 82 information contains 2 sub-options: Circuit ID and Remote ID, which define the relationship
between end device IP and the DHCP Option 82 server. The “Circuit ID” is a 4-byte number generated by the
Ethernet switch—a combination of physical port number and VLAN ID. The format of the “Circuit ID” is as
described below:
FF–VV–VV–PP
Where the first byte “FF” is fixed to “01”, the second and the third byte “VV-VV” is formed by the port VLAN ID
in hex, and the last byte “PP” is formed by the port number in hex. For example,
01–00–0F–03 is the “Circuit ID” of port number 3 with port VLAN ID 15.
The “Remote ID” is to identify the relay agent itself and it can be one of the following:
1. The IP address of the relay agent.
2. The MAC address of the relay agent.
3. A combination of IP address and MAC address of the relay agent.
4. A user-defined string.
Using Diagnosis
The S8000 series provides two important tools for administrators to diagnose network systems.