From jacobson@math-cs.cns.uni.edu Tue Feb 21 21:32:48 2006
Date: Tue, 21 Feb 2006 15:32:11 -0600 (CST)
From: Mark Jacobson <jacobson@math-cs.cns.uni.edu>
To: 810-023-01@uni.edu
Subject: [810-023-01] CSMA/CD, repeater, segment definitions

Hi 023 students,

Do not forget there is a quiz on Thursday, February 23rd.  This Thursday.

>From the http://www.cisco.com/univercd/cc/td/doc/cisintwk/ita/c12.htm

       which is linked to from our web page:
                                  http://www.cns.uni.edu/~jacobson/c023.html
     See the
     Networking terms and concepts - This LAN is your LAN. This LAN in my LAN
       link from our class web page to look up networking terms and concepts.

     http://www.cisco.com/univercd/cc/td/doc/cisintwk/ita/index.htm

CSMA/CD:
carrier sense multiple access collision detect. Media-access mechanism 
wherein devices ready to transmit data first check the channel for a 
carrier. If no carrier is sensed for a specific period of time, a device 
can transmit. If two devices transmit at once, a collision occurs and is 
detected by all colliding devices. This collision subsequently delays 
retransmissions from those devices for some random length of time. 
Ethernet and IEEE 802.3 use CSMA/CD access.

Repeater:
Device that regenerates and propagates electrical signals between two 
network segments.  See also segment.

Segment:
1. Section of a network that is bounded by bridges, routers, or switches.

2. In a LAN using a bus topology, a segment is a continuous electrical
    circuit that often is connected to other such segments with repeaters.

3. Term used in the TCP specification to describe a single transport layer
    unit of information. The terms datagram, frame, message, and packet
    also are used to describe logical information groupings at various layers
    of the OSI reference model and in various technology circles.


    See you on Thursday in Wright 105.  We might go to Physics 300 next
week for class.                           -----
    Mark