Vpi And Vci; Multiplexing; Vc-Based Multiplexing; Llc-Based Multiplexing - ZyXEL Communications Prestige 791R User Manual

as a DHCP client on the WAN port and so the IP Address and ENET ENCAP Gateway fields are not
applicable (N/A) as they are assigned to the Prestige by the DHCP server.
7.4

VPI and VCI

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.
7.5

Multiplexing

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.

7.5.1 VC-based Multiplexing

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.

7.5.2 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, for example, if charging heavily depends on
the number of simultaneous VCs.
7.6

Traffic Shaping

Traffic Shaping is an agreement between the carrier and the subscriber to regulate the average rate and
"burstiness" or fluctuation of data transmission over an ATM network. This agreement helps eliminate
congestion, which is important for transmission of real time data such as audio and video connections.
Internet Access
Prestige 791R G.SHDSL Router
7-3