Pppoe; Chapter 30 Pppoe; Pppoe Intermediate Agent Overview; Pppoe Intermediate Agent Tag Format - ZyXEL Communications GS3700 Series User Manual

This chapter describes how the Switch gives a PPPoE termination server additional information that
the server can use to identify and authenticate a PPPoE client.

30.1 PPPoE Intermediate Agent Overview

A PPPoE Intermediate Agent (PPPoE IA) is deployed between a PPPoE server and PPPoE clients. It
helps the PPPoE server identify and authenticate clients by adding subscriber line specific
information to PPPoE discovery packets from clients on a per-port or per-port-per-VLAN basis
before forwarding them to the PPPoE server.
PPPoE Client

30.1.1 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 135 PPPoE Intermediate Agent Vendor-specific Tag Format
Tag_Type
(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.

30.1.2 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.
Table 136 PPPoE IA Circuit ID Sub-option Format: User-defined String
SubOpt Length
0x01 N
(1 byte) (1 byte)
C
PPPoE IA
Tag_Len Value
String
(63 bytes)
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HAPTER
PPPoE Server
i1 i2
Value
3 0

PPPoE