Nat; Metric; Traffic Shaping - ZyXEL Communications P-660HW-Tx v3 User Manual

Chapter 5 Internet (WAN) Setup
a nailed-up connection. The first is that idle timeout is disabled. The second is that
the ZyXEL Device will try to bring up the connection when turned on and
whenever the connection is down. A nailed-up connection can be very expensive
for obvious reasons.
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.

5.5.6 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.

5.6 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
For example, if the normal route has a metric of "1" and the traffic-redirect route
has a metric of "2", 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.

5.7 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.
106
Section 5.2 on page
Section 5.9 on page 109)
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P-660HW-Tx v3 User's Guide