Vpi & Vci; Multiplexing; Vc-Based Multiplexing; Llc-Based Multiplexing - ZyXEL Communications Prestige 643 User Manual

Adsl router

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Prestige 643 ADSL Router

3.9

VPI & VCI

Be sure to use the correct Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI) numbers

supplied by the telephone company. The valid range for the VPI is 0 to 255 and for the VCI is 32 to 65535

(0 to 31 is reserved for local management of ATM traffic). Please see the Appendices for more

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, e.g., VC1

carries IP, VC2 carries IPX, 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, e.g., if charging heavily depends on the

number of simultaneous VCs.

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

methods.

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 i.e., it encapsulates routed Ethernet frames into

bridged ATM cells. ENET ENCAP requires that you specify a gateway IP address in the Ethernet

Encapsulation Gateway field in Menu 4 and in the Rem IP Addr field in Menu 11.1. You can get this

information from your ISP.

Internet Access

3-11

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Troubleshooting