Chapter 6 LAN Screens

6.3 DHCP

The ZyWALL can use DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132) to automatically assign IP addresses subnet masks, gateways, and some network information like the IP addresses of DNS servers to the computers on your LAN. You can alternatively have the ZyWALL relay DHCP information from another DHCP server. If you disable the ZyWALL’s DHCP service, you must have another DHCP server on your LAN, or else the computers must be manually configured.

6.3.1 IP Pool Setup

The ZyWALL is pre-configured with a pool of IP addresses for the computers on your LAN. See Chapter 49 on page 693 for the default IP pool range. Do not assign your LAN computers static IP addresses that are in the DHCP pool.

6.4 RIP Setup

RIP (Routing Information Protocol, RFC 1058 and RFC 1389) allows a router to exchange routing information with other routers. RIP Direction controls the sending and receiving of RIP packets. When set to Both or Out Only, the ZyWALL will broadcast its routing table periodically. When set to Both or In Only, it will 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.

RIP Version controls the format and the broadcasting method of the RIP packets that the ZyWALL sends (it recognizes both formats when receiving). RIP-1is universally supported; but RIP-2carries more information. RIP-1 is probably adequate for most networks, unless you have an unusual network topology.

Both RIP-2Band RIP-2Msend routing data in RIP-2 format; the difference being that RIP- 2B uses subnet broadcasting while RIP-2Muses 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.

By default, RIP Direction is set to Both and RIP Version to RIP-1.

6.5 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

 

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ZyWALL 2WG User’s Guide