The physical network stack
5th
September 2006
For a while I've been trying to work out what the difference is between the road and rail network. Specifically, I'd like to know why the rail network was fantastically successful in the 19th and early 20th centuries, but has been comprehensively beaten by the road network in the later 20th century.
In order to make comparisons easy I have decided to split physical networks (as opposed to data) into a stack:
- Pathway layer
- Link layer
- Vehicle layer
- Object layer
By way of example I have created this table of a few choice networks:
| RoyalMail™ | Rail | Road | |
|---|---|---|---|
| Pathway | Any of the other physical networks | Track | Motorways (freeways), roads, tracks, fields (depending on vehicle), the rail network, ferries |
| Link | Sorting office, postbox | Stations, terminals | Gates, road junctions, garages |
| Vehicle | Envelope, parcel | Rolling stock | Cars (and taxis), lorries (trucks), buses (including coaches), tanks, tractors, combine harvesters, motorcycles, bicycles |
| Object | Any inanimate object up to 20Kg | Pretty much anything | Pretty much anything |
From this a few interesting questions arise. For each network:
- who controls each of the layers,
- by how much,
- and how does that control affect other users?
I'll admit that I haven't thought about those yet, but hopefully this exercise has brought me closer to answering my original question. I'm just not quite sure how.