SGS-6341-Series User Manual

responds to PADO (PPPoE Active Discovery
Offer) packet to client according to the
received source MAC address of PADI packet; the packet will take server name and
service name.
3. Client sends PADR packet: For the third step, client selects a server to process the
session according to the received PADO packet. It may receive many PADO packets
for PADI. Message of the first step may be sent to many servers (select the server
according to whether the service information of PADO packet matches with the
service information needed by client). MAC address of the other end used for
session will be known after server is selected, and send PADR (PPPoE Active
Discovery Request) packet to it to announce the session requirements of server.
4. Server responds to PADS packet: For the fourth step, server establishes a session
ID according to the received PADR packet. This session ID will be sent to client
through PADS (PPPoE Active Discovery Session-confirmation) packet, hereto
PPPoE discovery stage is completed to enter session stage.
PADT (PPPoE Active Discovery Terminate) packet is a special packet of PPPoE. Its Ethernet
protocol number (0x8863) is the same as the above four packets, so it can be considered a
packet of discovery stage. To stop a PPPoE session, PADT may be sent at the discretional
time of the session. (It can be sent by client or server)
PPPoE Intermediate Agent supplies a function that identifies and locates the user. When
passing network access device, PADI and PADR messages will be sent by client with the
access link tag of this device at PPPoE discovery stage so as to exactly identify and locate the
user on server.
If the direct-link access device is LAN switch, the added information includes: MAC, Slot ID,
Port Index, Vlan ID and so on. This function is implemented according to Migration to
Ethernet-based DSL aggregation.
51.1.2.1 PPPoE Intermediate Agent Exchange Process
PPPoE Intermediate Agent exchange process is similar to PPPoE exchange process, for the
first exchange process, the access link tag is added to PADI and PADR packets. The
exchange process is as follows:
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User’s Manual of SGS-6341 series