Wan Technical Reference; Encapsulation - ZyXEL Communications P-793H v3 User Manual

6.5 WAN Technical Reference

This section provides some technical background information about the topics covered in this
chapter.

6.5.1 Encapsulation

Be sure to use the encapsulation method required by your ISP. The P-79X supports the following
methods.
6.5.1.1 ENET ENCAP
The MAC Encapsulated Routing Link Protocol (ENET ENCAP) is only implemented with the IP
network protocol. IP packets are routed between the Ethernet interface and the WAN interface and
then formatted so that they can be understood 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.
6.5.1.2 PPP over Ethernet
The P-79X supports PPPoE (Point-to-Point Protocol over Ethernet). PPPoE is an IETF Draft standard
(RFC 2516) specifying how a personal computer (PC) interacts with a broadband modem (DSL,
cable, wireless, etc.) connection. The PPPoE option is for 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).
One of the benefits of PPPoE is the ability to let 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 P-79X (rather than individual computers), the computers on
the LAN do not need PPPoE software installed, since the P-79X does that part of the task.
Furthermore, with NAT, all of the LANs' computers will have access.
6.5.1.3 RFC 1483
RFC 1483 describes two methods for Multiprotocol Encapsulation over ATM Adaptation Layer 5
(AAL5). The first method allows multiplexing of multiple protocols over a single ATM virtual circuit
(LLC-based multiplexing) and the second method assumes that each protocol is carried over a
separate ATM virtual circuit (VC-based multiplexing). Please refer to RFC 1483 for more detailed
information.
Chapter 6 WAN Setup
P-79X Series User's Guide
59