Chapter 31 PPPoE

31.1.2.2 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 Switch 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”.

Table 99 PPPoE IA Circuit ID Sub-option Format: Defined in WT-101

SubOpt

Length

 

 

 

 

Value

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0x01

N

Access

Space

eth

Space

Slot

/

Port No

:

VLAN

(1 byte)

(1 byte)

Node

(1

(3

(1

ID

(1

(2

(1

ID

Identifier

 

 

 

 

byte)

byte)

byte)

(1

byte)

byte)

byte)

(4

 

 

 

 

 

(20 byte)

 

 

 

byte)

 

 

 

bytes)

 

 

 

 

 

 

 

 

 

 

 

31.1.3 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.

 

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XGS4700-48F User’s Guide