Chapter 7 LAN

Please note that DNS proxy works only when the ISP uses the IPCP DNS server extensions. It does not mean you can leave the DNS servers out of the DHCP setup under all circumstances. If your ISP gives you explicit DNS servers, make sure that you enter their IP addresses in the LAN Setup screen. This way, the ZyXEL Device can pass the DNS servers to the computers and the computers can query the DNS server directly without the ZyXEL Device’s intervention.

7.1.5 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 ZyXEL Device will broadcast its routing table periodically and incorporate the RIP information that it receives.

•In Only - the ZyXEL Device will not send any RIP packets but will accept all RIP packets received.

•Out Only - the ZyXEL Device will send out RIP packets but will not accept any RIP packets received.

•None - the ZyXEL Device 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 ZyXEL Device sends (it recognizes both formats when receiving). RIP-1is 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-2Band RIP-2Msends the routing data in RIP-2 format; the difference being that RIP-2Buses subnet broadcasting while RIP-2Muses multicasting.

7.1.6 Multicast

Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 sender - 1 recipient) or Broadcast (1 sender - everybody on the network). Multicast delivers IP packets to a group of hosts on the network - not everybody and not just 1.

IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to establish membership in a Multicast group - it is not used to carry user data. IGMP version 2 (RFC 2236) is an improvement over version 1 (RFC 1112) but IGMP version 1 is still in wide use. If you would like to read more detailed information about interoperability between IGMP version 2 and version 1, please see sections 4 and 5 of RFC 2236. The class D IP address is used to identify host groups and can be in the range 224.0.0.0 to 239.255.255.255. The address

224.0.0.0is not assigned to any group and is used by IP multicast computers. The address

224.0.0.1is used for query messages and is assigned to the permanent group of all IP hosts (including gateways). All hosts must join the 224.0.0.1 group in order to participate in IGMP. The address 224.0.0.2 is assigned to the multicast routers group.

 

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P-2302HWUDL-P1 Series User’s Guide