From dbb4777ba78c6abac5bde7f2e418b505de5f8bfc Mon Sep 17 00:00:00 2001 From: wb2osz Date: Sun, 5 Mar 2023 15:10:05 +0000 Subject: [PATCH] More comments. --- src/digipeater.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/src/digipeater.c b/src/digipeater.c index 006ee7b..4daf189 100644 --- a/src/digipeater.c +++ b/src/digipeater.c @@ -164,7 +164,34 @@ void digipeater (int from_chan, packet_t pp) /* * First pass: Look at packets being digipeated to same channel. * - * We want these to get out quickly. + * We want these to get out quickly, bypassing the usual random wait time. + * + * Some may disagree but I followed what WB4APR had to say about it. + * + * http://www.aprs.org/balloons.html + * + * APRS NETWORK FRATRICIDE: Generally, all APRS digipeaters are supposed to transmit + * immediately and all at the same time. They should NOT wait long enough for each + * one to QRM the channel with the same copy of each packet. NO, APRS digipeaters + * are all supposed to STEP ON EACH OTHER with every packet. This makes sure that + * everyone in range of a digi will hear one and only one copy of each packet. + * and that the packet will digipeat OUTWARD and not backward. The goal is that a + * digipeated packet is cleared out of the local area in ONE packet time and not + * N packet times for every N digipeaters that heard the packet. This means no + * PERSIST times, no DWAIT times and no UIDWAIT times. Notice, this is contrary + * to other packet systems that might want to guarantee delivery (but at the + * expense of throughput). APRS wants to clear the channel quickly to maximize throughput. + * + * http://www.aprs.org/kpc3/kpc3+WIDEn.txt + * + * THIRD: Eliminate the settings that are detrimental to the network. + * + * * UIDWAIT should be OFF. (the default). With it on, your digi is not doing the + * fundamental APRS fratricide that is the primary mechanism for minimizing channel + * loading. All digis that hear the same packet are supposed to DIGI it at the SAME + * time so that all those copies only take up one additional time slot. (but outward + * located digs will hear it without collision (and continue outward propagation) + * */ for (to_chan=0; to_chanfilter_str[from_chan][to_chan]); if (result != NULL) { dedupe_remember (pp, to_chan); - tq_append (to_chan, TQ_PRIO_0_HI, result); + tq_append (to_chan, TQ_PRIO_0_HI, result); // High priority queue. digi_count[from_chan][to_chan]++; } } @@ -207,7 +234,7 @@ void digipeater (int from_chan, packet_t pp) save_digi_config_p->filter_str[from_chan][to_chan]); if (result != NULL) { dedupe_remember (pp, to_chan); - tq_append (to_chan, TQ_PRIO_1_LO, result); + tq_append (to_chan, TQ_PRIO_1_LO, result); // Low priority queue. digi_count[from_chan][to_chan]++; } }