ZyXEL Communications 650HW User Manual

Prestige 650HW ADSL Router User’s Guide 

3-16 

Internet Access 

Be sure to use the correct Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI) numbers 
supplied by your 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, 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. 

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 for instance, 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.