[aprssig] APRS Message Idea
Phillip B. Pacier
ad6nh at arrl.net
Fri Mar 4 18:19:13 EST 2005
Announcements and Bulletins in UI-View do utilize a decay method, which
is clearly outlined in the instruction manual. With regard to general
messaging, no, there is no decay rate, and perhaps that would be a
useful tool for the reasons you describe below. However, there are
other checks and balances in UI-View to prevent flooding of message packets.
73
Phil - AD6NH
Wes Johnston wrote:
>Bob's right about this one though.... the decay is the way to go. One of the
>things I thought was so cool about TCP/IP when I started playing packet was
>that TCP/IP would back off exponentially when attempting to deliver a packet,
>as opposed to the dumber ax.25 'fixed timing with a little randomness' method.
>When delivering packets onto a network, with TCP/IP it would start out pretty
>agressive but back off quickly if the link turned out slow. AX.25 on the other
>hand could send a packet over a long link, and if set aggressivly enough, would
>send the same packet again twice before the ACK got back. Not very effecient.
>
>Also, there's another advantage to the decay. Let's say that I send a message
>right now. about 1 minute later, you send a message. They collide because you
>pressed enter at the same time my station resent a copy of my message.
>
>Now in a fixed timing system where we each retry every minute, we will always
>collide.
>
>In a decay timing system, my message's next TX interval is 2 minutes from now.
>Your's is 10 seconds from now. We don't collide again. The point is that even
>when our timings match up every once in a while, our interval to the next TX
>time is different and we won't collide again for a good long while.
>
>I wish more APRS clients used the decay model.
>Wes
>
>
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