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By Greg Shultz, TechRepublic:
Implement an intraoffice messaging system with PopMessenger

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LAN Chat

Network settings

Overview

PopMessenger uses UDP protocol for basic communications between computers. UDP settings are very important for proper work of PopMessenger. There are two available communication modes (both use UDP protocol): UDP Broadcast and IP Multicast.

Please note All computers within your network should use either UDP Broadcast or IP Multicast communication mode in order to communicate with each other.

UDP Broadcast mode

UDP Broadcast mode can be used in small networks when IP Multicast mode can not be used for some reason.

Broadcast addresses

In this list you can specify broadcast addresses that PopMessenger should use to send UDP packets.

For example, imagine that all computers in your network (or subnetwork) have addresses like 10.10.10.x and subnet mask is 255.255.255.0. In this case you should remove the address 255.255.255.255 from the field and add new address - 10.10.10.255.

However, for most small non-segmented networks you should keep the default 255.255.255.255 address.

You can also add an exact IP-addresses of a single computers (this is useful, for example, when you want to communicate via PopMessenger with Internet or RAS-connected user or when a particular LAN-computer is simply invisible by other users for some reason).

IP Multicast mode

In comparison to UDP Broadcasts, IP Multicast is a bandwidth-conserving technology that greatly improves interoperability in routed environment and allows traffic-friendly group messages. IP Multicast mode is the default and preferred mode since it is better suited for internal corporate broadcasts. It allows you to communicate with users of your own network segment, external network segments and even with remote users over Internet. You should always use IP Multicast unless you have some limitations or problems with it.

IP Multicast group address

IP Multicast is based on the concept of a group that has its own unique group address. Please note that each PopMessenger within your network should belong to the same group and use one group address in order to communicate with each other. However, you may find this setting very useful when, for example, you want to split your network into several different segments - in that case you need to assign different addresses for each such segment.

The valid IP range for this setting is 224.0.1.0 ... 238.255.255.255. Some addresses can be reserved.

Network scope (IP time-to-live)

This setting defines network scope for outgoing UDP packets. For simple non-segmented networks the value of 1 will be enough.

UDP port

This setting allows you to specify the port that PopMessenger should use to send and receive UDP packets in both Multicast and Broadcast modes. It is strongly recommended to keep the default value (8473) for this setting untouched. Please note that each PopMessenger within your network should use the same port number in order to communicate with each other. However, you may find this setting very useful when, for example, you want to split your network into several different PopMessenger-powered segments (neighborhoods) - in that case you need to assign a different port values for each such segment.

TCP port

This port PopMessenger should use to send and receive files. It is also strongly recommended to keep the default value (8474).