ZyXEL Communications P-2612HW-F1 -, Руководство пользователя

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Chapter 6 WAN Setup
P-2612HW Series User’s Guide
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IP Assignment with RFC 1483 Encapsulation
In this case the IP address assignment must be static.
IP Assignment with ENET ENCAP Encapsulation
In this case you can have either a static or dynamic IP. For a static IP you must fill
in all the IP Address and Gateway IP Address fields as supplied by your ISP.
However for a dynamic IP, the ZyXEL Device acts as a DHCP client on the WAN
port and so the IP Address and Gateway IP Address fields are not applicable
(N/A) as the DHCP server assigns them to the ZyXEL Device.
6.5.5 Nailed-Up Connection (PPP)
A nailed-up connection is a dial-up line where the connection is always up
regardless of traffic demand. The ZyXEL Device does two things when you specify
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.
6.5.6 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.
6.5.7 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. 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.