ZyXEL Communications Prestige 645R, User Manual

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Prestige P645 ADSL Internet Access Router
3-2 Internet Access
The subnet mask specifies the network number portion of an IP address. Your Prestige will compute the
subnet mask automatically based on the IP address that you entered. You don’t need to change the subnet
mask computed by the Prestige unless you are instructed to.
3.2.2 Private IP Addresses
Every machine on the Internet must have a unique address. If your networks are isolated from the Internet,
e.g., only between your two branch offices, you can assign any IP addresses to the hosts without problems.
However, the Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of IP
addresses specifically for private networks:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
You can obtain your IP address from the IANA, from an ISP, or have it assigned by a private network. If you
belong to a small organization and your Internet access is through an ISP, the ISP can provide you with the
Internet addresses for your local networks. On the other hand, if you are part of a much larger organization,
you should consult your network administrator for the appropriate IP addresses.
Regardless of your particular situation, do not create an arbitrary IP address;
always follow the guidelines above. For more information on address assignment,
please refer to RFC 1597, Address Allocation for Private Internets and RFC 1466,
Guidelines for Management of IP Address Space.
3.2.3 RIP Setup
RIP (Routing Information Protocol) allows a router to exchange routing information with other routers. The
RIP Direction field controls the sending and receiving of RIP packets. When set to both, the Prestige will
broadcast its routing table periodically and incorporate the RIP information that it receives; when set to none,
it will not send any RIP packets and will ignore any RIP packets received.
The Version field controls the format and the broadcasting method of the RIP packets that the Prestige sends
(it recognizes both formats when receiving. RIP-1 is universally supported; but RIP-2 carries more
information. RIP-1 is probably adequate for most networks, unless you have an unusual network topology.
Both RIP-2B and RIP-2M send the routing data in RIP-2 format; the difference being that RIP-2B uses
subnet broadcasting while
RIP-2M
uses multicasting. Multicasting can reduce the load on non-router
machines since they generally do not listen to the RIP multicast address and so will not receive the RIP
packets. However, if one router uses multicasting, then all routers on your network must use multicasting,
also.