[Year 12 SofDev] Software development key knowledge

[Timmer-Arends]

Hello Heath

> if I understand correctly TCP/IP has four layers that kind of match up to layers 2-7 of the OSI model. The relationship to the physical layer is that layers 2-7 of the OSI and 1-4 of TCP/IP relate to the physical layer in 
>the same way. Sound correct??? This leads me to the question of why doesn't TCP/IP have an additional physical layer at the bottom??


 It sort of does and it doesn't. Apprently there is some contention about how to map TCP/IP onto OSI. As far as I can make out that's because the bottom layer of TCP/IP ('link' layer?) basically specifies how TCP/IP hooks into another standard, for example, ethernet. Ethernet itself incorporates the physical and data link layers, so in effect TCP/IP gets two for the price of one. But technically, within itself TCP/IP does not address physical layer issues at all.



Regards

Robert T-A
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