Creating The Ppp Interface - HP ProCurve 7000dl Series Basic Management And Configuration Manual

ADSL WAN Connections
PPPoE Overview
Step 3. The devices use network control protocol (NCP) frames to enable
the exchange of Network Layer protocols, such as IP, across the link.
Step 4. The devices use PPP frames to transmit the actual data.
(For more information about establishing a PPP session, see Chapter 6:
Configuring the Data Link Layer Protocol for E1, T1, and Serial Interfaces.)
During the process of establishing a PPP session, the devices will also nego-
tiate the maximum receive unit (MRU) size. For PPPoE, the negotiated MRU
cannot be larger than 1492 bytes because Ethernet has a maximum payload
size of 1500 bytes. The PPPoE header is 6 bytes, and the PPP protocol ID is 2
bytes. With this overhead of 8 bytes, the PPP MTU cannot be larger than
1492 bytes.

Creating the PPP Interface

To configure PPPoE, you first configure the ADSL interface, the ATM inter-
face, and the ATM subinterface. (These instructions begin with "Configuring
the ADSL Interface: the Physical Layer" on page 7-12.) When configuring the
ATM subinterface, you must set the encapsulation to aal5snap or aal5mux
ppp, as shown below:
Syntax: encapsulation aal5snap
or
Syntax: encapsulation aal5mux [ip | ppp]
Your service provider should tell you which encapsulation to use.
Setting the encapsulation type configures the ATM adaptation layer (which is
called Layer 2-1). When you use PPPoE, you must also configure the ATM
point-to-point layer (which is called Layer 2-2). To configure this layer, you
create a PPP interface and then bind this interface to the ATM subinterface.
To create a PPP interface, move to the global configuration mode context
and enter:
Syntax: interface <interface> <number>
Replace <interface> with ppp and replace <number> with a number to
distinguish this PPP interface from other PPP interfaces created on the router.
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