ZyXEL GS1920 Series User Guide - Page 232
PPPoE Intermediate Agent Tag Format, Sub-Option Format, Flexible Circuit ID Syntax with Identifier
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Chapter 28 PPPoE 28.1.2.1 PPPoE Intermediate Agent Tag Format If the PPPoE Intermediate Agent is enabled, the Switch adds a vendor-specific tag to PADI (PPPoE Active Discovery Initialization) and PADR (PPPoE Active Discovery Request) packets from PPPoE clients. This tag is defined in RFC 2516 and has the following format for this feature. Table 104 PPPoE Intermediate Agent Vendor-specific Tag Format Tag_Type Tag_Len Value i1 i2 (0x0105) 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 Suboption". They have the following formats. Table 105 PPPoE IA Circuit ID Sub-option Format: User-defined String SubOpt Length Value 0x01 N String (1 byte) (1 byte) (63 bytes) Table 106 PPPoE IA Remote ID Sub-option Format SubOpt Length 0x02 N MAC Address or String (1 byte) (1 byte) (63 bytes) Value 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- GS1920 Series User's Guide 232