Everything on today's EtherWAN × JAM Services agenda — the OSI model, Layers 1–3, and the hands-on lab — in about 30 minutes. Read, tap, and walk in ready.
🔊 Tap Listen on any section for free narration (uses your device's built-in voice — no data, no account).
ITS = Intelligent Transportation Systems. It's the tech in the traffic cabinet and along the road that keeps vehicles moving safely — and the network is the nervous system that ties it all back to the Traffic Management Center (TMC).
Signal controllers (ATC / 2070 / Cobalt), CCTV cameras, vehicle detection (loops, radar, video), ramp meters, and Dynamic Message Signs.
A roadside 332 / ITS cabinet where power, the controller, and the network switch all live. Hot in summer, freezing in winter — hardware must survive both.
Fiber or wireless links carrying data from each intersection to the TMC, often chained intersection-to-intersection down a corridor.
Operators watch cameras, retime signals, and push updates. Every packet you'll learn about today ends up here.
EtherWAN builds the hardened Ethernet switches, media converters, and PoE gear that live inside traffic cabinets. Think "office switch, but built to survive the road."
A map for "where does my problem live?" The OSI model stacks networking into 7 layers. Today lives in the bottom 3 — tap each to expand.
Mnemonic (bottom → top):
Physical · Data Link · Network · Transport · Session · Presentation · Application
As your data goes down the stack to leave the switch, each layer adds its own header. Tap play.
The cables, connectors, and signals themselves — copper, fiber, and light/electricity. This is "is it plugged in and is the link light on?"
Cheap, easy to terminate. Max 100 m per run. Picks up electrical noise & can carry surges — risky outdoors.
Carries light. Goes km, immune to EMI & lightning. Single-mode = long haul; Multi-mode = shorter, in-building.
Where switches work. Devices are identified by MAC addresses, grouped by VLANs, and protected by ring redundancy.
Burned-in 48-bit hardware ID, e.g. 00:1B:44:11:3A:B7. Unique per device.
The L2 package: dest MAC + src MAC + data. Switches forward frames.
Learns "MAC X = port 3" so it forwards, not floods.
One physical switch, three virtual networks. Tap a device, then tap the VLAN it belongs in. (Cameras ≠ signal control ≠ management.)
4 intersections in a ring. One path is the active loop; a backup segment sits idle. Cut a link — recovery in <15 ms.
Where IP addresses and routers live. Layer 2 moves frames inside one network; Layer 3 moves packets between networks — all the way to the TMC.
Switch = same network, uses MAC (L2). Router = between networks, uses IP (L3). Many EtherWAN units do both (L2/L3).
The "exit door" IP a device uses to reach anything outside its own subnet — e.g. the path back to the TMC.
To send to an IP on the same subnet, a device asks "who has 10.0.5.20?" and learns its MAC. That's ARP tying Layer 3 to Layer 2.
Static = fixed, hand-set IP (ITS standard — the TMC always finds it). DHCP = auto-assigned; rare for field gear.
32 bits, written as 4 octets (0–255). The subnet mask / CIDR draws the line between the network part and the host part.
Private ranges you'll live in (never routed on the public internet):
ITS networks almost always use 10.x.x.x — huge room to give every corridor & intersection its own block.
Type any IP and pick a mask — it computes the whole block. This is the tool you'll reach for in the field.
| CIDR | Subnet mask | Total | Usable hosts | Typical use |
|---|
Device 10.0.5.20 (/24) wants to reach these. Direct or via router?
You'll configure a real managed EtherWAN switch. Below is a realistic intersection build — the exact shape of what you'll do — plus a working terminal to practice on.
Corridor block 10.0.5.0/24 · mask 255.255.255.0 · gateway (router to TMC) 10.0.5.1. Every field device gets a fixed static IP:
| Device | IP address | VLAN |
|---|---|---|
| Router / Gateway → TMC | 10.0.5.1 | 99 mgmt |
| EtherWAN switch (mgmt) | 10.0.5.10 | 99 mgmt |
| Signal controller (Cobalt/2070) | 10.0.5.20 | 20 control |
| CCTV camera #1 | 10.0.5.30 | 10 cctv |
| CCTV camera #2 | 10.0.5.31 | 10 cctv |
| Video detection | 10.0.5.40 | 10 cctv |
Next intersection down the corridor = 10.0.6.0/24, then 10.0.7.0/24… the router carries traffic between them and up to the TMC.
Plug your laptop into a switch port (or console). Set your laptop to the same subnet first, e.g. 10.0.5.100 / 255.255.255.0. Link light solid = Layer 1 is good.
So you can reach its web UI / CLI. Web UI: System → IP Config. CLI equivalent:
Keep cameras, control, and management separate on the one physical switch:
Enable Alpha-Ring on the two fiber uplink ports (to the neighbor intersections) for <15 ms failover:
Ping the gateway and a neighbor. Four replies = you're done. 🎉 Practice it in the terminal below.
You're logged into the switch at 10.0.5.10. Run real commands — type help or tap a chip.
No pressure — instant explanations.
Tap to flip. Skim these on the drive over.