Chapter 28 PPPoE
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defined in the DSL Forum Working Text (WT)-101. The default access node identifier is the host
name of the PPPoE intermediate agent and the eth indicates “Ethernet”.
28.1.2.3 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. You
can also specify the agent sub-options (circuit ID and remote ID) that the Switch adds to PADI and
PADR packets from PPPoE clients.
Trusted ports are connected to PPPoE servers.
• If a PADO (PPPoE Active Discovery Offer), PADS (PPPoE Active Discovery Session-confirmation),
or PADT (PPPoE Active Discovery Terminate) packet is sent from a PPPoE server and received on
a trusted port, the Switch forwards it to all other ports.
• If a PADI or PADR packet is sent from a PPPoE client but received on a trusted port, the Switch
forwards it to other trusted port(s).
Note: The Switch 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.
• If a PADI, PADR, or PADT packet is sent from a PPPoE client and received on an untrusted port,
the Switch adds a vendor-specific tag to the packet and then forwards it to the trusted port(s).
• The Switch discards PADO and PADS packets which are sent from a PPPoE server but received on
an untrusted port.
28.2 The PPPoE Screen
Use this screen to configure the PPPoE Intermediate Agent on the Switch.
Click Advanced Application > PPPoE in the navigation panel to display the screen as shown.
Click Click Here to go to the Intermediate Agent screen.
Figure 142 Advanced Application > PPPoE Intermediate Agent
Table 85 PPPoE IA Circuit ID Sub-option Format: Defined in WT-101
SubOpt Length Value
0x01
(1 byte)
N
(1 byte)
Access
Node
Identifier
(20 byte)
Space
(1
byte)
eth
(3
byte)
Space
(1
byte)
Slot
ID
(1
byte)
/
(1
byte)
Port No
(2
byte)
:
(1
byte)
VLAN
ID
(4
bytes)
