Ethernet 10BASE-T1S¶
This chapter outlines the INET Framework’s implementation of select features from the IEEE 802.3cg-2019 standard. Specifically, it covers 10BASE-T1S in both point-to-point and multidrop topologies, utilizing the Physical Layer Collision Avoidance (PLCA) protocol.
Overview¶
The Ethernet 10BASE-T1S model is a distinct implementation from the INET Framework’s default Ethernet model. Although the default The 10BASE-T1S model re-implements the default model’s CSMA/CD functionality to have separate CSMA/CD MAC and CSMA/CD PHY layers. This separation is essential for incorporating the Physical Layer Collision Avoidance (PLCA) protocol between the MAC and PHY layers. The new model is geared towards multidrop link topologies and it offers the following modules for this purpose:
EthernetPlcaHost models a network node suitable for use in multidrop links
EthernetPlcaInterface models a network interface suitable for use in multidrop links
EthernetPlca implements the Ethernet Physical Layer Collision Avoidance (PLCA) protocol
EthernetCsmaMac implements the Ethernet CSMA/CD MAC protocol suitable for use with PLCA
EthernetCsmaPhy implements the Ethernet CSMA/CD PHY protocol suitable for use with PLCA
EthernetMultidropLink implements the single twisted-pair cable suitable for use in multidrop links
Additionally, the model incorporates modules non-specific to 10BASE-T1S:
WireJunction represents a universal wiring hub suitable for use in multidrop links
Point-to-point links¶
For the Ethernet 10BASE-T1S point-to-point communication mode the default Ethernet model can be used, more specifically the EthernetLink channel and the EthernetInterface module. In the network interface, the full-duplex EthernetMacPhy module can be employed.
Multidrop links¶
To construct an Ethernet 10BASE-T1S multidrop link, connect multiple EthernetPlcaHost modules together. Utilize EthernetMultidropLink channels and WireJunction modules to establish the network topology. Set the cable length for each connection to define the signal propagation delay.
For mixed networks, you can incorporate other network node modules like StandardHost, EthernetSwitch, or TsnSwitch. Replace their network interface directed towards the multidrop link with an EthernetPlcaInterface module. Make sure every interface connected to the multidrop link utilizes the EthernetPlcaInterface module.
Result analysis¶
The 10BASE-T1S modules offer various statistics useful for evaluating network node performance on a multidrop link. For a comprehensive list of statistics, check the EthernetCsmaMac, EthernetPlca, and EthernetCsmaPhy modules.
Key statistics are:
queue length
MAC state machine state
PLCA transmit opportunity ID
PLCA control state machine state
PLCA data state machine state
PHY state machine state
PHY transmitted signal type
PHY received signal type
Understanding the operation of a multidrop network interface can become quite complex. Consider creating a chart with multiple subplots and a shared X-axis, displaying various statistics simultaneously. To create such a chart:
select the desired statistics on the ‘Browse data’ page of the result analysis tool
choose ‘Plot using line chart on separate axis with Matplotlib’ from the context menu
open the chart configuration dialog, go to the ‘Line’ tab and enable ‘Display enums as colored strips’.
Note
For long running simulations, the recorded statistical results may grow large, causing chart performance to degrade, especially for the colored strips displaying state machine states. To address this issue, open the chart configuration dialog and specify a start/end time on the ‘Input’ tab to narrow down the data to the relevant portion.