Preparation for Recitation 9
Thursday, March 4th
Read the Ethernet: Distributed Packet Switching for Local Computer
Networks paper (from the course packet) by
Metcalfe and Boggs. Skip sections 5 and 7. This paper is
a classic one about the design of the Ethernet. Ethernet was a
crucial component to the development of LANs, and its success has
played a major role in the success of the Internet. Although the
current Ethernets differ substantially from the description in the
paper, the ideas are highly relevant and partially used in many
systems including wireless local area networks (LANs).
Ethernet is a broadcast network. Thus, as you read this paper you
need to understand how packets are delivered from a sender to a
receiver, what the potential difficulties are, and how they are
Before reading the paper, read Chapter 7.1 and 7.8 of the
notes. The latter section provides a brief overview of
Ethernet using the terminology and concepts of 6.033.
As usual, start out by reading the abstract, Section 2 titled
"System Summary", and conclusion. This should give you a
high-level idea about the content of the paper. Scan the paper for
section and subsection titles, to give yourself an idea of how it
fits together. Then, read the whole paper. In particular, read
carefully sections 2, 3, 3.3, 3.5 and 4.4. Check the figures and
skim through the rest of the paper.
While reading, try to answer the following questions:
- What's a broadcast network?
- What is a "packet collision"? Why does it happen?
- How does the design of Ethernet improve the probability that
packets are successfully delivered, despite the potential for
- There is no single machine that controls when and who gets to use
the shared medium. This is a decentralized design. Can you think
of some advantages and disadvantages of this
- Can one use the Ethernet design to build the Internet? (I.e., can
one build a very big network with millions of machines using the
P.S. If you feel uncomfortable with the content of the paper or
have any problem answering the above questions, then browse on
ahead into 7.2 and 7.3 of the notes.