Chapter 28 PPPoE
XS1930 Series User’s Guide
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The Tag_Type is 0x0105 for vendor-specific tags, as defined in RFC 2516. The Tag_Len indicates the
length of Value, i1 and i2. The Value is the 32-bit number 0x00000DE9, which stands for the “ADSL Forum”
IANA entry. i1 and i2 are PPPoE intermediate agent sub-options, which contain additional information
about the PPPoE client.
28.1.2.2 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.
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.
WT-101 Default Circuit ID Syntax
If you do not configure a Circuit ID string for a specific VLAN on a port or for a specific port, and disable
the flexible Circuit ID syntax in the
PPPoE > Intermediate Agent
screen, the Switch automatically
generates a Circuit ID string according to the default Circuit ID syntax which is defined in the DSL Forum
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)
