User's Manual

Table Of Contents
Chapter 5 WAN Setup 47
5.5 WAN Technical Reference
This section provides some technical background information about the topics covered in this
chapter.
5.5.1 Encapsulation
Be sure to use the encapsulation method required by your ISP. The Device supports the following
methods.
5.5.1.1 ENET ENCAP
The Device only implements the MAC Encapsulated Routing Link Protocol (ENET ENCAP) with the IP
network protocol. IP packets get routed between the Ethernet interface and the WAN interface and
then formatted to work in a bridged environment. For instance, it encapsulates routed Ethernet
frames into bridged ATM cells. ENET ENCAP requires that you specify a gateway IP address in the
Gateway IP Address field in the wizard or WAN screen. You can get this information from your ISP.
5.5.1.2 PPP over Ethernet
The Device supports PPPoE (Point-to-Point Protocol over Ethernet). PPPoE specifies how a personal
computer (PC) interacts with a broadband modem (DSL, cable, wireless, etc.) connection. The PPPoE
option provides a dial-up connection using PPPoE.
For the service provider, PPPoE offers an access and authentication method that works with
existing access control systems (for example RADIUS).
PPPoE lets you access one of multiple network services, a function known as dynamic service
selection. This enables the service provider to easily create and offer new IP services for individuals.
Operationally, PPPoE saves significant effort for both you and the ISP or carrier, as it requires no
specific configuration of the broadband modem at the customer site.
By implementing PPPoE directly on the Device (rather than individual computers), the computers on
the LAN do not need PPPoE software installed, since the Device does that part of the task.
Furthermore, with NAT, all of the LANs’ computers will have access.
5.5.1.3 PPPoA
PPPoA stands for Point to Point Protocol over ATM Adaptation Layer 5 (AAL5). A PPPoA connection
functions like a dial-up Internet connection. The Device encapsulates the PPP session based on RFC
1483 and sends it through an ATM PVC (Permanent Virtual Circuit) to the Internet Service Provider’s
(ISP) DSLAM (Digital Subscriber Line (DSL) Access Multiplexer). Please refer to RFC 2364 for more
information on PPPoA. Refer to RFC 1661 for more information on PPP.