Zyxel OLT2412 [287/326] Port state

OLT2412 User’s Guide 287

CHAPTER 42

PPPoE IA

This chapter describes how the OLT gives a PPPoE termination server additional information that the

server can use to identify and authenticate a PPPoE client.

42.1 PPPoE Intermediate Agent Overview

• PPPoE allows ISPs to manage accounts access from dial-up Internet (such as ADSL).

• A PPPoE Intermediate Agent (PPPoE IA) is deployed between a PPPoE server and PPPoE clients.

Figure 66 PPPoE IA in Network

• PPPoE IA helps the PPPoE server identify and authenticate clients by adding subscriber line

specific information to PPPoE discovery packets (PADI, PPPoE Active Discovery Initiation, and

PADR, PPPoE Active Discovery Request) from clients on a per-port or per-port-per-VLAN basis

before forwarding them to the PPPoE server.

• PPPoE Intermediate Agent is defined in “DSL Forum Technical Report 101-Migration to Ethernet-

Based DSL Aggregation” (TR-101).

• If a PADI or PADR packet exceeds 1500 octets after adding the subscriber line specific

information, the PPPoE IA does not send the packet to the PPPoE server but sends the packet

with a Generic-Error TAG back to the sender (client).

42.1.1 Port State

Every port is either a trusted port or an untrusted port for the PPPoE intermediate agent. This

setting is independent of the trusted/untrusted setting for DHCP snooping or ARP inspection. PPPoE

IA inserts access loop identification in the packets sent from non-trusted ports to trusted ports. You

can also specify the agent sub-options (circuit ID and remote ID) that the OLT adds to PADI and

PADR packets from PPPoE clients.

Trusted ports are connected to PPPoE servers.

Note: The OLT will drop all PPPoE discovery packets if you enable the PPPoE intermediate

agent and there are no trusted ports.

Untrusted ports are connected to subscribers.

PPPoE IA

PPPoE Server

PPPoE Client