![background image](http://html1.mh-extra.com/html/zyxel-communications/p-660r-f1-series/p-660r-f1-series_user-manual_945302046.webp)
Chapter 4 WAN Setup
P-660R-F1 Series User’s Guide
46
Do not specify a nailed-up connection unless your telephone company offers flat-rate service or you
need a constant connection and the cost is of no concern
4.1.7 NAT
NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in
a packet, for example, the source address of an outgoing packet, used within one network to a
different IP address known within another network.
4.2 Metric
The metric represents the "cost of transmission". A router determines the best route for
transmission by choosing a path with the lowest "cost". RIP routing uses hop count as the
measurement of cost, with a minimum of "1" for directly connected networks. The number must be
between "1" and "15"; a number greater than "15" means the link is down. The smaller the
number, the lower the "cost".
The metric sets the priority for the ZyXEL Device’s routes to the Internet. If any two of the default
routes have the same metric, the ZyXEL Device uses the following pre-defined priorities:
• Normal route: designated by the ISP (see
)
• Traffic-redirect route (see
• WAN-backup route, also called dial-backup (see
For example, if the normal route has a metric of "1" and the traffic-redirect route has a metric of
"2" and dial-backup route has a metric of "3", then the normal route acts as the primary default
route. If the normal route fails to connect to the Internet, the ZyXEL Device tries the traffic-redirect
route next. In the same manner, the ZyXEL Device uses the dial-backup route if the traffic-redirect
route also fails.
If you want the dial-backup route to take first priority over the traffic-redirect route or even the
normal route, all you need to do is set the dial-backup route’s metric to "1" and the others to "2"
(or greater).
IP Policy Routing overrides the default routing behavior and takes priority over all of the routes
mentioned above.
4.3 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.
Summary of Contents for P-660R-F1 series
Page 2: ......
Page 8: ...Certifications P 660R F1 Series User s Guide 8 ...
Page 16: ...P 660R F1 Series User s Guide 16 ...
Page 18: ...P 660R F1 Series User s Guide 18 ...
Page 62: ...Chapter 4 WAN Setup P 660R F1 Series User s Guide 62 ...
Page 104: ...Chapter 7 Firewalls P 660R F1 Series User s Guide 104 ...
Page 140: ...Chapter 9 Certificates P 660R F1 Series User s Guide 140 ...
Page 144: ...Chapter 10 Static Route P 660R F1 Series User s Guide 144 ...
Page 162: ...Chapter 12 Dynamic DNS Setup P 660R F1 Series User s Guide 162 ...
Page 190: ...Chapter 15 System P 660R F1 Series User s Guide 190 ...
Page 204: ...Chapter 16 Logs P 660R F1 Series User s Guide 204 ...
Page 212: ...Chapter 18 Diagnostic P 660R F1 Series User s Guide 212 ...
Page 216: ...Chapter 19 Troubleshooting P 660R F1 Series User s Guide 216 ...
Page 220: ...P 660R F1 Series User s Guide 220 ...
Page 222: ...P 660R F1 Series User s Guide 222 ...
Page 246: ...P 660R F1 Series User s Guide 246 ...
Page 250: ...P 660R F1 Series User s Guide 250 ...
Page 258: ...P 660R F1 Series User s Guide 258 3 Click OK to close the window Figure 172 Java Sun ...
Page 266: ...P 660R F1 Series User s Guide 266 ...
Page 267: ...P 660R F1 Series User s Guide 267 ...
Page 268: ...P 660R F1 Series User s Guide 268 ...