ZyXEL Communications OLT2406 - Page 253

Chapter 29 PPPoE
OLT2406 User’s Guide
253
example is “OLT/07/0123” and indicates the PPPoE packets come from a PPPoE client which is
connected to the OLT’s port 7 and belong to VLAN 123.
29.1.2.4 WT-101 Default Circuit ID Syntax
If you do not configure a Circuit ID string for a specific VLAN on a port or for a specific port, and disable
the flexible Circuit ID syntax in the PPPoE > Intermediate Agent screen, the OLT automatically generates
a Circuit ID string according to the default Circuit ID syntax which is 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”.
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 OLT 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 OLT 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 OLT forwards it
to other trusted port(s).
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.
• If a PADI, PADR, or PADT packet is sent from a PPPoE client and received on an untrusted port, the OLT
adds a vendor-specific tag to the packet and then forwards it to the trusted port(s).
• The OLT discards PADO and PADS packets which are sent from a PPPoE server but received on an
untrusted port.
Table 98 PPPoE IA Circuit ID Sub-option Format: Using Identifier String and Variables
SubOpt Length Value
0x01
(1 byte)
N
(1 byte)
Identifier
String
(53 byte)
delimiter
(1 byte)
Slot ID
(1 byte)
delimiter
(1 byte)
Port No
(2 byte)
delimiter
(1 byte)
VLAN ID
(4 bytes)
Table 99 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)
Spac
e
(1
byte)
eth
(3
byte)
Spac
e
(1
byte)
Slot ID
(1
byte)
/
(1
byte)
Port No
(2 byte)
:
(1
byte)
VLAN ID
(4
bytes)