Prestige 782R G.SHDSL Router

3.4.1 VPI and VCI

Be sure to use the correct VPI (Virtual Path Identifier) and VCI (Virtual Channel Identifier) numbers supplied by the telephone company. Valid range for VPI is 0 to 255 and for the VCI is 32 to 65535 (1 to 31 is reserved for local management of ATM traffic).

3.4.2 Multiplexing

Two conventions are used in identifying what protocols the virtual circuit (VC) is carrying. Be sure to use the multiplexing method required by your ISP.

VC-based Multiplexing

In this case, by prior mutual agreement, each protocol is assigned to a specific virtual circuit, e.g., VC1 carries IP, VC2 carries IPX, etc. VC-based multiplexing may be dominant in environments where dynamic creation of large number of ATM VCs is fast and economical.

LLC-based Multiplexing

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, e.g., if charging heavily depends on the number of simultaneous VCs.

3.4.3 Encapsulation

Be sure to use the encapsulation method required by your ISP. The Prestige supports the following methods:

PPP

Select this option when the peer is using a “PPP over ATM” networking model. Please refer to RFC-2364 for more information on PPP over ATM Adaptation Layer 5 (AAL5). Refer to RFC-1661 for more information on PPP.

RFC-1483

Select this option when the peer is using a “Multi-protocol over ATM” networking model. RFC-1483 describes two methods for Multi-protocol 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.

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