Introduction to Networking

* About this course
* What's a network?
* What are the fundamental ideas?
* What's the Internet? How do these ideas play out there?

About This Course

* There are 40 of us. I have another 40 starting Capstone
  right now. This is the most students I've had at PSU.

* The course will be run off a Moodle LMS I run:

    http://svcs.cs.pdx.edu/moodle/cs594

  You need to get signed up as a student on the Moodle if
  you are not already. You then need to *separately* enroll
  in this course on the Moodle. (Using signup key given in
  class.)

  This must be done *now*. A week from tomorrow I will go
  through the roll and administratively drop anyone not
  hooked into Moodle from the course. In the meantime, I may
  well send relevant announcements to the course forum.

Prerequisites

* You must be reasonably OK at C programming (or willing to
  learn it fairly quickly). C is the official language of
  the Internet and therefore this course; I'm not interested
  in others.

* You must have some idea how to interact with the UNIX
  (Linux) operating system. UNIX is the official OS of the
  Internet and therefore this course; I'm not interested in
  others.

* You must have good reading and research skills. We will be
  reading a huge pile of material in this course, and you
  will need to find some of it yourself.

* You need to have time and willingness to explore on your
  own.

Textbook

* Stevens vol. I 2nd ed is
  * Awesome
  * Encyclopedic
  * Huge

* We will read most of the textbook this quarter. Given its
  volume, your reading may not be so detailed in spots, but
  you can't just skip it, either. Use good judgement.

* Bring textbook to every class meeting, also something to
  write on and with.

Homework and Final

* I will give assignments as frequently as my schedule (not
  yours) permits. They will all be programming
  assignments. I will not accept them late or busted.

* We have lab facilities if you fail to have access to your
  own computer running Linux. Make sure you have access to
  them now.

* See the syllabus re academic honesty. I get really unhappy
  with plagiarists.

* The Final will be at the scheduled time. It will be
  closed-book and cover mostly concepts (little if any
  code).

Grading Philosophy

* I would love to give everyone an A. It's your job to make
  that possible.

* Part of the reason for homework / quizzes / etc is to
  justify the A I am giving you.

Course Philosophy

* Networking is a big, interrelated topic.

* Three organizing principles:
  * Vocabulary
  * Mechanisms
  * Design and Implementation

* Accelerating learning curve.

Communications Basics

* "Medium", "Transmit", "Receive", "Bit": Sending things
  over a "wire" of some sort.

* "Bandwidth", "Latency", "Throughput", "Error Rate": Wires
  have limits.

* "Flow Control", "Packets", "Synchronization": Communication
  should be managed.

* "Topology": Who can talk to who?

  * One nodes: "loopback"
  * Two nodes: "point-to-point"
  * Three or more endpoints: various graph topologies,
    notably "shared", "bus", "star", "loop".

Error Correction and Flow Control

* Two basic error correction strategies

  * "Forward Error Correction" ("redundancy" first)

  * "Retransmission" (redundancy later): This is what
    networking protocols usually use

* "Flow Control": Receiver(s) need to keep up with
  transmitter. Commonly same(ish) mechanism for
  retransmission and flow control.

* Internet is "best effort" delivery: may lose or reorder
  packets due to errors or flow control issues.

* Trad. Internet soln: "TCP"

Layered Model

* Networks are often built up in layers.
  * 7-layer ISO OSI model.
  * "5-layer" Internet model.

* A simplified layer model:
  * Application: HTTP
  * Service: e.g. TCP
  * Transport: e.g. IP
  * Link: e.g. MAC
  * Physical: e.g. Ethernet

* Different layers may have different topologies.

Packets, Paths, Addresses and Routing

* For HW reasons (etc) data is broken up into blocks called
  "packets", which are sent separately.

* Each packet traverses a "path" through its network
  following some "route", hopefully arriving at its
  destination.

* "Packet-switched" networks are "store-and-forward":
  packets arrive at intermediate nodes and are held there
  until they can be sent on.

* Each packet carries a descriptor called its "address". The
  address may serve three functions:
  * Destination ID
  * Destination Location
  * Routing

* Addresses may identify a "host" or "interface"---usually
  an interface.

Reading About Networks

* The "Internet Engineering Task Force (IETF)" is the
  organization that builds and maintains the Internet.

* IETF has a "Request For Comments (RFC)" process that it
  uses. Nothing is officially adopted by IETF without
  progressing through draft RFC status. Each RFC must have
  two independent implementations before being adopted.

* To learn about the Internet you can use the textbook, but
  you also need to learn to find and read RFCs.

* There is specific language in RFCs that matters: "MAY"
  "MUST" "SHOULD" "WILL" and their negations.

* Reading RFCs requires network vocabulary and patience.