ZyXEL Communications MGS3700-12C - Sub-Option Format

Chapter 32 PPPoE
MGS3700-12C User’s Guide
318
32.2.1 Sub-Option Format
There are two types of sub-option: “Agent Circuit ID Sub-option” and “Agent
Remote ID Sub-option”. They have the following formats.
The 1 in the first field identifies this as an Agent Circuit ID sub-option and 2
identifies this as an Agent Remote ID sub-option. The next field specifies the
length of the field. The Switch takes the Circuit ID string you manually configure
for a VLAN on a port as the highest priority and the Circuit ID string for a port as
the second priority. In addition, the Switch puts the PPPoE client’s MAC address
into the Agent Remote ID Sub-option if you do not specify any user-defined string.
32.2.1.1 Flexible Circuit ID Syntax with Identifier String and Variables
If you do not configure a Circuit ID string for a VLAN on a specific port or for a
specific port, the Switch adds the user-defined identifier string and variables into
the Agent Circuit ID Sub-option. The variables can be the slot ID of the PPPoE
client, the port number of the PPPoE client and/or the VLAN ID on the PPPoE
packet.
The identifier-string, slot ID, port number and VLAN ID are separated from each
other by a pound key (#), semi-colon (;), period (.), comma (,), forward slash (/)
or space. An Agent Circuit ID Sub-option example is “Switch/07/0123” and
indicates the PPPoE packets come from a PPPoE client which is connected to the
Switch’s port 7 and belong to VLAN 123.
Table 103 PPPoE IA Circuit ID Sub-option Format: User-defined String
SubOpt Length Value
0x01
(1 byte)
N
(1 byte)
String
(63 bytes)
Table 104 PPPoE IA Remote ID Sub-option Format
SubOpt Length Value
0x02
(1 byte)
N
(1 byte)
MAC Address or String
(63 bytes)
Table 105 PPPoE IA Circuit ID Sub-option Format: Using Identifier String and
Variables
SubOpt Length Value
0x01
(1 byte)
N
(1 byte)
Identifier
String
(53 byte)
delimiter
(1 byte)
Slot ID
(1 byte)
delimiter
(1 byte)
Port No
(2 byte)
delimiter
(1 byte)
VLAN ID
(4 bytes)