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Improved Layer-2 Protocol    by Nino Carillo, KK4HEJ

page modified June 12, 2022

This page has a copy of a PDF describing the protocol implemented in IL2P mode of the NinoTNCs.

The IL2P protocol has history in the NinoTNC and in Direwolf software, and was described in a paper delivered to the 2020 TAPR DCC. The IL2P enhancements included repacking the callsign fields and AX.25 bits, while maintaining compatability with the KISS AX.25 framing. Until June 2022, IL2P was exclusively used for 1200 baud and faster FM packet radio. A NinoTNC, using any of the FM 1200 baud or faster data modes, having conducted transmissions at other than 1200 AX.25, will send out an AX.25 beacon identifying the callsign used for the TNC and giving the shortened URL leading to this page.

As of version 0.5, the Weak-Signal-Extentions were added. This adds several features to the protocols. The automatic ID transmission described for the FM/1200-baud and faster modes, described above, is still in place in the NinoTNCs, including NinoTNCs running the newer versions of the IL2P modes, but the automatic ID feature is not enabled if the lower speed SSB modes are selected.

Feel free to download the IL2P specification just below. You are encouraged to consider implementing the spec and to ask questions on the ninotnc@groups.io email reflector.

v0.5 of the IL2P specification

Sept 2020 TAPR DCC presentation by Nino KK4HEJ [Youtube]

© Rene Nino Carrillo and Tadd Torborg, 2020↝2022 -- all rights reserved