ZyXEL Communications Prestige 662HW Series, User Manual

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Prestige 662HW Series User’s Guide
7-2 WAN Setup
By implementing PPPoE directly on the Prestige (rather than individual computers), the computers on
the LAN do not need PPPoE software installed, since the Prestige does that part of the task.
Furthermore, with NAT, all of the LANs’ computers will have access.
7.4 Traffic Shaping
Traffic Shaping is an agreement between the carrier and the subscriber to regulate the average rate and
fluctuations 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.
Peak Cell Rate (PCR) is the maximum rate at which the sender can send cells. This parameter may be
lower (but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a maximum
speed of 832Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed because it is
dependent on the line speed.
Sustained Cell Rate (SCR) is the mean cell rate of each bursty traffic source. It specifies the maximum
average rate at which cells can be sent over the virtual connection. SCR may not be greater than the
PCR.
Maximum Burst Size (MBS) is the maximum number of cells that can be sent at the PCR. After MBS
is reached, cell rates fall below SCR until cell rate averages to the SCR again. At this time, more cells
(up to the MBS) can be sent at the PCR again.
If the PCR, SCR or MBS is set to the default of “0”, the system will assign a maximum value that
correlates to your upstream line rate.
The following figure illustrates the relationship between PCR, SCR and MBS.
Figure 7-1 Example of Traffic Shaping
7.5 Zero Configuration Internet Access
Once you turn on and connect the Prestige to a telephone jack, it automatically detects the Internet
connection settings (such as the VCI/VPI numbers and the encapsulation method) from the ISP and
makes the necessary configuration changes. In cases where additional account information (such as an
Internet account user name and password) is required or the Prestige cannot connect to the ISP, you
will be redirected to web screen(s) for information input or troubleshooting.