Michel,
your drawing of TCP/IP is NOT the model I used in the design of TCP/IP.
At the time Bob Kahn and I were working on this design, there were
three networks being used to support the Internet: ARPANET, Packet
Radio net and Packet Satellite net. These networks were packet switched
and they had physical and link layers as well as network layers.
so we had IP/network/link/physical layers
IP was a layer above the nominal "network" layer.
Things got more complex as routers were implemented that ran IP over
dedicated links rather than servings as gateways between packet nets.
However, even with routers operating at IP layer primarily, there were
lower layer networks such as frame relay, ATM, over which IP operated.
If there was any confusion, it was that packet radio, arpanet and packet
satellite networks had both layer two and layer three elements while
Frame Relay and ATM tended to be characterized as layer 2 networks.
vint
At 04:29 PM 10/6/2002 -0700, Michel Py wrote:
If I had to design a model it would be:
Michel's TCP/IP OSI
model model model
+--------------+ +---------------+ +---+--------------+
! ! ! ! ! 7 ! Application !
! ! ! ! +---+--------------+
! Application ! ! Application ! ! 6 ! Presentation !
! ! ! ! +---+--------------+
! ! ! ! ! 5 ! Session !
+--------------+ +---------------+ +---+--------------+
! Transport ! ! Transport ! ! 4 ! Transport !
+--------------+ +---------------+ +---+--------------+
! Network ! ! Internet ! ! 3 ! Network !
+--------------+ +---------------+ +---+------+-------+
! Logical Link ! ! ! ! ! Data ! LLC !
+--------------+ ! Network ! ! 2 ! Link +-------+
! Media Access ! ! Interface ! ! ! ! MAC !
+--------------+ ! ! +---+------+-------+
! Physical ! ! ! ! 1 ! Physical !
+--------------+ +---------------+ +---+--------------+
I understand that people that have used the TCP/IP model don't care much
of what's inside the Network Interface layer, but there is a bunch of
stuff there that could use layering. That's why, short of having my very
own model drawn above, I keep using the OSI one for
explanatory/educational purposes.
Michel.
Vint Cerf
SVP Architecture & Technology
WorldCom
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