How Do We Route Traffic?

Post date: Feb 3, 2019 3:25:00 PM

Most VHF traffic nets are thought of as "local": the "first mile" or "last mile" of the system: involved in traffic relay only as needed to receive traffic to deliver, or to relay traffic originated. With a footprint of approximately 10 counties, VHF contact to EMA stations at the county and state level, as well as stations able to relay traffic to other radio services including MARS and SHARES, COTN has a good deal more relaying than many other "local" nets.

COTN net control stations and stations that can perform relay services therefore need to pay attention to traffic listed, and the capabilities of stations on frequency.

A good example of how this can work took place in the past week. We had routine precedence traffic listed for Hardin County, about 50 miles from our primary repeater's transmit site, about 30 miles from the nearest receive site for the repeater system. Normally traffic going that far would be outbound, headed to HF.

A station in Marion County, about 40 miles from our transmit site and 20 miles from the nearest receive site, volunteered to take the Hardin County traffic. He advised us that there as a weekly net in Marion County that evening that often had a Hardin County station check in. Though it is not an NTS or RRI affiliate, the net would handle the traffic under the care of the Marion County operator.

Thus, rather than waiting for the next cycle for HF and finding a station in or near Hardin County to take the traffic, the message got through and was delivered correctly by relaying through two nets in about 45 minutes. The attached image shows the relative positions of the sites in question.

We note that especially as we consider times where sunspot activity or other atmospheric conditions impede HF operations, the ability to employ relay to ensure timely delivery is an important part of providing a resilient and reliable message relay service.