TCP Versus UDP for Alarm Transmission

In a discussion on the Alarm Monitoring Group (LinkedIn), a person from the alarm industry posed the following question: "Why is the security Industry going against worldwide recommendations and accepted understanding on UDP? TCPIP is safe reliable and accepted by all networks."

The case for TCP

A supporter continued "TCP's transport mechanism can and should be used as a reliable method of delivery of a message, it has all the built in checks and stops required to guarantee that a message will arrive at the Alarm Receiving Center. If you send a message using TCP it will arrive... period, or the sender will know its not, which is exactly the same as the alarm industry messaging overhead."

The case for UDP

A manufacturer of well known signalling equipment responded stating that "UDP, with a proprietary transmission protocol creates a safer, more secure and efficient Alarm Signalling Solution for use with all types of network. It has been chosen by SIA and the EN working groups to provide a standard with a transmission protocol to ensure safe delivery, acknowledgement and management within the transceivers."

Steve Nutt from IP Alarms questioned the argument against UDP as follows: "I think the argument that UDP is unreliable was raised by someone 30 years ago that did not understand anything about networks. It is carried on today by people that also obviously have no understanding of real world applications. If you send a packet and you get a response - your packet got there. If there is no response - it didn't get there - send it again. I don't know what is unreliable about that?"

A Real World Example

One group member tried to put the problem into real world terms by saying "When you send a letter that is important one uses registered mail as it provides a proof of delivery/reception. When it's an not so important correspondence one sends it by regular mail. This is what we all do on a day to day basis. In IP communication TCP is the same as a registered mail. One becomes proof of delivery/reception. UDP is comparable to standard mail. Most of the time it works but sometimes it is late or gets lost."

One reply to that example was that "Registered mail is not a good example of reliable delivery. It is an audit trail that can be viewed when either the sender or the recipient find out that an expected package has not arrived. The loop is not closed by a formal acknowledgment. In the UK system you can go on line to see if it arrived. This might not be a good strategy for Intruder Alarms!" Another one was that "A UDP mailman delivers his packages in a Ferrari while the TCP mailman uses a truck."

It's not just about alarm transmission

Steve Nutt pointed out that "As we all know, getting alarm signals from a panel to the server is only one part of the problem. Many alarm panels also provide the ability for the alarm company to remotely program it using a modem and software in the alarm company office. If anyone can tell me how you can support the upload/download of every make and model of alarm panel on the market over TCP, then I'd be very interested to hear about it. We do it using UDP." He then continued by saying "Many markets focus more on how best to solve the problem at hand and common sense is the order of the day. Ease of use and cost efficiency play an important role. Sometimes the most appropriate solution will involve using the benefits that UDP provides and to point blank say that it should never be used is nonsense."

In Summary

A supporter of UDP summarised as follows: "Your comments would suggest that using UDP would be a disaster, unusable and unworkable. This is not true, is far from the truth and there are tens of thousands of systems in the field proving the point."

The discussion continues on. If you are interested in getting involved in discussions about the alarm monitoring industry, then get on over to LinkedIn and fill out your application to join the Alarm Monitoring Group.