ZyXEL Communications P-660H - VERSION 3.40, User Manual

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P-660H/HW/W-T Series User’ Guide
Chapter 6 WAN Setup 92
6.1.4.2 IP Assignment with RFC 1483 Encapsulation
In this case the IP Address Assignment must be static with the same requirements for the IP
Address and ENET ENCAP Gateway fields as stated above.
6.1.4.3 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 ENET ENCAP Gateway fields as supplied by your ISP. However for a
dynamic IP, the Prestige acts as a DHCP client on the WAN port and so the IP Address and
ENET ENCAP Gateway fields are not applicable (N/A) as the DHCP server assigns them to
the Prestige.
6.1.5 Nailed-Up Connection (PPP)
A nailed-up connection is a dial-up line where the connection is always up regardless of traffic
demand. The Prestige does two things when you specify a nailed-up connection. The first is
that idle timeout is disabled. The second is that the Prestige 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
6.1.6 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.
6.2 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 Prestige’s routes to the Internet. If any two of the default
routes have the same metric, the Prestige uses the following pre-defined priorities:
• Normal route: designated by the ISP (see Section 6.7 on page 95 )
• Traffic-redirect route (see Section 6.8 on page 98 )
• WAN-backup route, also called dial-backup (see Section 6.9 on page 99 )