ZyXEL Prestige 660HW-D1 Wireless Router 91-004-593003B Manual Do Utilizador

P-660H/HW-D Series User’s Guide

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Chapter 5 WAN Setup

By implementing PPPoE directly on the ZyXEL Device (rather than individual computers), 
the computers on the LAN do not need PPPoE software installed, since the ZyXEL Device 
does that part of the task. Furthermore, with NAT, all of the LANs’ computers will have 
access.

PPPoA stands for Point to Point Protocol over ATM Adaptation Layer 5 (AAL5). A PPPoA 
connection functions like a dial-up Internet connection. The ZyXEL Device encapsulates the 
PPP session based on RFC1483 and sends it through an ATM PVC (Permanent Virtual 
Circuit) to the Internet Service Provider’s (ISP) DSLAM (digital access multiplexer). Please 
refer to RFC 2364 for more information on PPPoA. Refer to RFC 1661 for more information 
on PPP.

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 the RFC for more detailed information.

There are two conventions to identify what protocols the virtual circuit (VC) is carrying. Be 
sure to use the multiplexing method required by your ISP.

In this case, by prior mutual agreement, each protocol is assigned to a specific virtual circuit; 
for example, VC1 carries IP, etc. VC-based multiplexing may be dominant in environments 
where dynamic creation of large numbers of ATM VCs is fast and economical.

In this case one VC carries multiple protocols with protocol identifying information being 
contained in each packet header. Despite the extra bandwidth and processing overhead, this 
method may be advantageous if it is not practical to have a separate VC for each carried 
protocol, for example, if charging heavily depends on the number of simultaneous VCs.

For Internet access you should use the encapsulation and multiplexing methods used by your 
ISP. Consult your telephone company for information on encapsulation and multiplexing 
methods for LAN-to-LAN applications, for example between a branch office and corporate 
headquarters. There must be prior agreement on encapsulation and multiplexing methods