Subject: TCP/IP Terms

From: "Bill Cunningham" <[email-masked]>
Date: Fri, 27 Sep 2002 19:49:32 -0400

Vint,
    Some of us at IETF are thinking about a draft to clear up some
terminology about the different layers of TCP/IP.
Whether it be packet, datagram, segement (more clearly defined) or whatever
the case. Do you have any opinions on this?

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From: Christopher Evans <[email-masked]>
Date: Fri, 27 Sep 2002 20:52:17 -0800

I passed my midterm today, so let me give it a try.. 

LAYER 7 - APPLICATION - Your data manipulation applications :)
LAYER 6 - PRESENTATION - compression, encryption, char translation
LAYER 5 - SESSION  - your connection manager interface (i.e. BSD sockets)
LAYER 4 - TRANSPORT- data segmentation, with checksums
LAYER 3 - NETWORK  - Addressing (i.e. routing, routers.. or i like "rooters")
LAYER 2 - DATALINK - Bit-oriented encapsulation frames
LAYER 1 - PHYSICAL - .,';,.ELECTRICAL SIGNALS.,';,.

Segments are LAYER 4. Packets are LAYER 3. Frames are, duh, LAYER 2. 

Segments : also called PDUs, Protocol Data Units, a grouping of data gtom layers 
7,6, & 5 and provides reliability and error correction for transfer. 

--chris

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From: Christopher Evans <[email-masked]>
Date: Fri, 27 Sep 2002 21:02:00 -0800

datagram is confuse..   well best i understand is the whole stack layers all rolled 
into one logical grouping.