The picture

CS70 Network Fundamentals & Architecture

David Morgan
Santa Monica College
see syllabus for email address

 

Our curious network:

Not any Damsel, which her vaunteth most
In skilful knitting of soft silken Twine;
Nor any Weaver, which his Work doth boast,
In Diaper, in Damask, or in Lyne;
Nor any skill'd in Workmanship emboss'd;
Nor any skill'd in Loups of Fingring fine;
Might in their diverse Cunning ever dare
With this so curious Net-work to compare.
       Edmund Spenser

Administrativa

Course outline

Zoom meeting recordings

Homework schedule

Grade information

Home network map

Syllabus

SMC dates/deadlines

 

Reading list, per chapter:
 6th edition
 5th edition

Remote Unix accounts


TechInfo

Textbook's website

RFC lookup

Remote Unix access with ssh

Protocols: non-cyber examples

MAC address assignments
 - listing
 - search

TCP/IP - Intro to the IP Protocols

TCP/IP Pocket
Reference Guide
 - IPv4 version
 - IPv6 version

Wireshark doc
html   pdf

Network calculators:
  here's one
  and another
  and a third

Real world DSL
  - a DSL order
 -
Analysis

commercial routers


Selected protocols

ARP

IP

ICMP

TCP

UDP

echo (port 7)

discard (port 9)

chargen (port 19)

 


 

SPRING 2021
Section 1793  9:00a - 12:05p Saturdays remotely via Zoom

This Website (http://classpage.dmorgan.us/)  will be used extensively to communicate with you. Announcements, grade reports, and assignments will be posted here. You are responsible for awareness of the information posted here.

Announcements/grades/current topics

Images from/for the test - Canvas does not display some images if you use browsers that are not "up to date." A few of my questions do contain images. Depending on your browser you might not be able to see them. In case that happens to you during the test, I have made the images alternatively available here. You are free to look at them in advance of the test. (6/12)

Other courses I teach - are known to you from the main website front page. There, you can see the class-specific pages from recent semesters for a concrete idea of their exact content (particularly see the course outlines).

CS40 - Operating Systems (3hr credit, next offering Fall 2021)

CS41 - Linux Workstation Administration (3hr credit, next offering Summer 2021)

CS75 - Network Protocols further depth and variety on the topic beyond CS70 (unscheduled)

CS78 - Secure Server Installation & Administration (unscheduled) (6/5).

Posted - a new slide presentation about the dhcp protocol. The new link is in course outline section 14, entitled "dhcp". We will talk about dhcp, as well as apache, today. (6/5)

Second test - The SMC College District Calendar shows a final exam period June 8-15. We will have an online, non-cumulative Test2 on current topics, similar to our recent Test1 on the earlier topics. It will be on Saturday 6/12. I plan to schedule it within our regular class period that morning, from 10am till noon. It will be on Canvas, and I plan to be there in chat in real time, in case you want to ask any questions. (6/5)

Grades - have not been updated since last week, link entitled "Grade information" at left.  The dns assignment is yet to be graded. I will grade it shortly. Please call any other anomalies to my attention. (6/5)

Grades - have been updated, link entitled "Grade information" at left. They include the "connect classroom to internet" homework. Please check your grades and let me know of any anomalies. (5/29)

Second test - our final class meeting will be next Saturday 6/5. The SMC College District Calendar shows a final exam period June 8-15. We will have an online, non-cumulative Test2 on current topics, similar to our recent Test1 on the earlier topics. It will be on Saturday 6/12. I plan to schedule it within our regular class period that morning. (5/29)

Homework
do - the exercise at course outline section 7's link entitled "connect a classroom to the internet."  due on sputnik by end of day Thursday May 27. 
do - the exercise at course outline section 13's link entitled "dns name server -VirtualBox version"  due on sputnik by end of day Sunday May 30.  (5/21)

Grades - have been updated, link entitled "Grade information" at left. They include the tcp interactive dataflow homework. Please check your grades and let me know of any anomalies. (5/21)

Important name service files on linux computers -
 /etc/hosts  gives "mappings" that pair IP addresses with names
 /etc/resolv.conf  gives hard-coded IP addresses of one or two name servers to use
 /etc/services holds name-to-number mappings for udp and tcp ports (5/21)

Addresses, functions - you know them. Don't get them mixed up.

(5/21)

Homework
listen - to the podcast segment at course outline section 11's link entitled "tcp getting connected" which is a general description of the operation of tcp.
do - the exercise at course outline section 11's link entitled "tcp interactive dataflow tracking."  due on sputnik by end of day Thursday May 20. 
listen - to the dns training video at the link entitled "dns.avi" in course outline section 13 homework column, in anticipation of our next topic, the domain name system.
read - course outline reading column section 13 about "traditional internet applications
  in particular web, mail, and name (dns) service, emphasis on the latter which will
  be the topic at our next meeting May 22. (5/15)

Remaining calendar - beyond today there class meetings on 3 upcoming Saturdays:
 May 22
 May 29
 June 5
The SMC College District Calendar shows a final exam period June 8-15. I anticipate giving an online non-cumulative Test2 on current topics. It will be similar to our recent Test1 on the earlier topics. It will probably be scheduled for our class time Saturday, June 12. (5/15)

Grades - have been updated, link entitled "Grade information" at left. They include the xinetd "server manager" homework. Please check your grades and let me know of any anomalies. (5/15)

Grades - have been updated, link entitled "Grade information" at left. They include the test. Please check your grades and let me know of any anomalies. (5/8)

Homework
do - the "xinetd" assignment, which was posted below 5/1 and has now been assigned a due date.
listen - to the podcast segment at course outline section 11's link entitled "tcp getting connected" which is a general description of the operation of tcp.
anticipate - the exercise at course outline section 11's link entitled "tcp interactive dataflow tracking." It will be assigned next week.  (5/8)

Letter-upgrader variants - They bestow a protocol on the otherwise protocol-less original letter upgrader pair. The original client sends a letter to the original server, which robotically and single-mindedly sends the next letter of the alphabet back. The new versions allow either the next or previous letter to be returned. The client now has to tell the server which, and the server has to differentially respond accordingly. That's a protocol. (5/8)

Various services and the server programs and protocols they use.

Service Server Linux executable Protocol used
name BIND /usr/sbin/named dns
web APACHE /usr/sbin/httpd http
MS sharing SAMBA /usr/sbin/smbd smb
address DHCP /usr/sbin/dhcpd dhcp
socket demo CHOMPER /opt/socketdemo/byteme none
letter upgrade letter upgrade server4 none, really
letter upgrade letter upgrade v2 server4-with-protocol batp*

    *batp - bidirectional alphabet traversal protocol ?

(5/8)

Test - is published on Canvas. It will be available Sunday and Monday, May 2 and 3. It is timed, allowing 105 minutes from the time it is started. Take it any time Sunday or Monday. (You shouldn't start after 10:15pm Monday, as you will be cut off at midnight and not have a full 105 minutes.) (5/1)

Homework
do - the "xinetd" exercise. Mimic my performance of that exercise, whose written instructions are in course outline section 12. I expect to do the exercise step-by-step during our class meeting May 8. You may be able to complete it during the class, following along with me. If not, with aid of the Zoom class recording and the written instructions you can do it on your own. Submit a screenshot from CLIENT in which you access the "byteme" non-network program (networked with the aid of xinetd) at 192.168.1.1 to show its "GIGA-BYTE ME!" output on CLIENT's screen. Please name your screenshot file "xinetd.jpg" (or png). The exercise is done with the same two  machines you used to do the earlier "sniffing" homework. Re-use the scripts from that assignment to produce the two machines needed for this one.  due on sputnik by end of day Thursday May 13.  (5/1)

Grades - have been updated, link entitled "Grade information" at left. They include the internetworking assignment. Please check your grades and let me know of any anomalies. (4/24)

Homework
listen - to the "discussion of netstat" link in the Homework column of course outline section 12
read forward -
upcoming topics
 course outline reading column section 11 about udp and tcp
 course outline reading column section 10 about socket API programming (4/24)

Manufacture of first 4 nodes of the internet - Computers from different manufacturers could never communicate. By a deliberate indirect means, the internet enabled them to do that. The particular makes and models of the original four computers knit together in the original "Internet" were:
 at UCLA - a Sigma 7 made by Scientific Data Systems of Santa Monica, CA
 at Stanford - a 940 by Scientific Data Systems of Santa Monica, CA
 at UC Santa Barbara - an IBM 360 by International Business Machines of Armonk, NY
 at University of Utah - a PDP 10 by Digital Equipment Corp. of Maynard, MA
It remains heterogeneous today. It's why your Android on Samsung and my Windows on Hewlett-Packard can both access the same credit card or airline reservation databases on somebody's mainframe. (4/24)

Alternative internetworks - here are 3 variations on the theme of our "internetworking" assignment's topology. And here is an extended version of the "linear" internetwork that featured in our "internetworks" slides. There are some questions based on both these images and their topologies on the upcoming test. (4/23)

Test - for the upcoming test (see 4/3 posting below), here are some questions for you to consider. (4/15)

No class April 17, due to spring break. (4/10)

Homework -
do - the "exercise on internetworking on VirtualBox" in the "Homework" column of course outline section 8. A hands-on counterpart of this exercise, very similar, has been done in the classroom in the past. It involves making addressing and routing choices. I recorded the students' choices on the whiteboard.
Here is a photo of the whiteboard map of a class internetwork built by a previous class. We/you will do similarly. due on sputnik by Thursday April 22  (4/10)

Grades - have been updated, link entitled "Grade information" at left. They include the macip and error detection assignments. Please check your grades and let me know of any anomalies. (4/10)

1972 explanation of the Arpanet - the ARPA (Advanced Research Projects Agency) network which became the Internet. Listen to it optionally. I came upon it today and found it very interesting. See if you can grade these internet inventors on the accuracy of their predictions about the potential of their network. (4/4)

Grades - have been updated, link entitled "Grade information" at left. They include the "IP packet delivery" assignment featuring Sally and Harry. Please check your grades and let me know of any anomalies. (4/3)

Test - it will be time for a test once you have performed the internetworking homework exercise, which looks likely to be finished/due around April 20. So the test looks likely to fall somewhere in the April 20-30 time period. I will talk more about it in class before the test date. See the notations in the "Reading list, per chapter" (left-hand column of this page) indicating which portions of the textbook can be covered in the test. (4/3)

Spring break - is the week of April 12 per the SMC calendar. As affects us, we will meet as usual next Saturday 4/10 but not the Saturday thereafter 4/17. We will resume meeting Saturday 4/24, plus the next 6 Saturdays after that before we reach final exam week and course end. (4/3)

Homework - 
do - the activities in the "Homework" column of course outline section 9
 turning in "error detection," exercise there, due on sputnik by end of day Thursday 4/8,
listen - to the narrated slide presentation about the very important topic of internetworking. Find the link to it in course outline section 7. The link is entitled "(narrated version)". I will not make this presentation in our (Zoom) class. Instead I'll leave it to you to listen to it on your own. In class I will summarize these slides but you will need to see them fully, on your own, my abbreviated summary will not be enough. It is the foundation for the major lab exercise homework coming up in about a week. (4/3)

A real-world DSL order - We have been emphasizing what a "network" is in technical, mathematical terms. It's a range of numbers that people express by telling other people what the first number in the range is (network address), and how many numbers there are in it (netmask). This surfaces in the commnuique I received once when I ordered a subnet from an ISP. Please see the links in the column at left under the heading "Real world DSL." Read the analysis. (4/3)

Who was IANA? What about now? Where are they? What is their job? 
 (see also, RIRs) (4/3)

Grades - have been updated, link entitled "Grade information" at left. They include the "subnet partitioning" assignment. Please check your grades and let me know of any anomalies. (3/27)

Golden rules for deciding how to ship a packet (Fore Systems "IP packet delivery"):

We reviewed the concept behind the "IP packet delivery": if IP thinks a destination IP address is local it arps for that IP address, if not it arps for the IP address of its default router (which comes from the routing table). Everything hinges on what "local" means. That is a function of the given destination address, the local address, and the local netmask. Network calculators and/or the linux "ipcalc" command can help you recreate IP's "thinking process" in this regard for particular subnets, addresses, and netmasks.

A related description of the thinking process comes from our textbook, Computer Networks and Internets, Douglas Comer (see p. 368 fifth edition). (3/27)

Homework - 
read - everything in the Reading column of course outline section 7
listen - to the recorded demo of forwarding behavior differences of hubs vs switches, Homework column of course outline section 6 (do this at your convenience over the next 2 weeks). During the demo I drew
a sketch. It's of poor quality but available if you want to review it.
listen - to the podcast segment at the link entitled "packet delivery" in the Homework column of course outline section 6
do - "IP packet delivery," course outline section 7 Homework column. It was originally an on-paper assignment. Please do it on paper per the instructions, then scan the resulting 4 pages into 4 image files. Name them: 

 packet-delivery-harry.jpg
 packet-delivery-jim.jpg
 packet-delivery-sue.jpg
 packet-delivery-alice.jpg

(or alternatively use .png instead of .jpg filename extensions) and upload them to your assignments directory on the server. Don't use any other format. due on server by end-of-day Thursdsday April 1
do - "MAC vs IP addresses," course outline section 7 Homework column. due on server by end-of-day Monday April 5
(Both these assignments focus on the same understanding.) (3/27)

Grades - have been published, link entitled "Grade information" at left. They include the "netmask legality" exercise.. Please call any anomalies to my attention. (3/20)

Home network map - because sometimes in class I refer to my home network for illustration of certain points, I've made a diagram of it. (3/20)

Homework - 
read - material in course outline sections 5 and 7
do
- "subnet partitioning," course outline section 7 Homework column. You can do it on paper and send a scan or photo of the paper as a jpg or png file. Or you can put the same information into a text file using txt file extension. Turn in to spunik by end-of-day Thursday 3/25 
(3/20)

Double match?? - what would happen if an IP packet's destination address matched two entries in the routing table. To which of the two interfaces would it be sent? Is this even possible? (3/20)

Packet capture files for you from the "wireshark" in-class exercise
I performed the exercise while running Wireshark and saved the traffic into capture files. You can open my files in Wireshark, to replay and analyze what I did.

The IP addresses of the machines I used were 192.168.1.10 and 192.168.1.12. Those are reflected in the captures. Get the files (unzip) then open them in Wireshark. You can then ponder the questions the exercise asks and use the captures to help you understand. The files are:
 for section 4:  echo-udp.cap  echo-tcp.cap
 for section 7:  login-telnet.cap  login-ssh.cap
 for section 8:  http.cap 

Satisfy yourself you have a pretty good idea what you are looking at. In particular, compare the header structures you see in the captured frames with the ones mapped out in the TCP/IP Pocket Reference Guide. And, practice using Wireshark's "Follow TCP stream" feature, found by right-clicking on packets in the packet list pane. It will starkly and unmistakably extract the password used in the telnet login session. And it will reveal the content of the web page obtained in the http browse session. There is nothing to turn in.  (3/20)

Monday evening office hours - we will hold an office hours zoom meeting at 7pm tonight. The purpose is to address anything you like related to the mechanics of the VirtualBox VMs or the homework assignments we have been doing or the concepts we have been discussing. Use the same Zoom credentials that you do usually for regular Saurday class meetings. (3/15)

Packet encapsulation clarification - one of the slide presentations we viewed about ethernet provoked questions during lecture two weeks ago. It was about the relationship in a frame among the various protocols that appear within it. The word is "encapsulation." Think Russian dolls. Think one-inside-the-other. Please revisit the slide presentation and view the two slides shown on its page 8. The first one shows the general concept, better than it did before. The second one shows a real-world frame from a Wireshark capture, and breaks its content down into the protocol components within it. This real-world frame is one that was captured while performing the Wireshark sniffing homework making a telnet connection. (3/15)

Packet traffic composition - some of it is nugget, some is dross. Some of it is kernel, some is chaff.  "...traffic is composed of user and app oriented information [nugget] augmented by protocol information inserted for the benefit of network operation [chaff]." When we communicate information, why do we carry a lot of deadweight extra information around with it? When we mail paper letters, why do we send a lot of extra envelope paper along with it? For benefit of the delivery operation. (3/15)

Norm Abramson    4/1/1932 - 12/1/2020 

(3/13)+

Network Address  +  Netmask  =  Subnet
It's useful to think of a network (a.k.a. subnet) as being defined by a position, and an extent measured from that position, on the continuum of IP addresses represented as a number line. A network is definitively identified by a 2-component ID. The first is its network address and the second is its netmask. 

It is the network address that establishes the position or starting point of the address range or block that is the network. And it is the netmask that establishes its extent or size. As an example consider a network whose network address is 64.52.25.224 and whose netmask is 255.255.255.224 (the one that signifies "thirty-two" as size). The number line below is a microscopic segment of the number line for the whole internet. That number line is 4 billion addresses in length (because with 32 bits 4 billion is the number of distinct address values that can be composed). Here, with the first 24 bits of our address (64.52.25) we are narrowing in on a particular little 256-address segment within that number line. Within the segment, the network address further positions us with final precision. This idea of sectioning off the 4 billion addresses into separately addressable subordinate pieces is called subnetting, and the resulting pieces or address groups are called subnets.

64.52.25.224/255.255.255.224:

A short accompanying, explanatory recorded explanation of performing subnetting.

(3/13)

>>Partial homework answer<<
In class we tested the "netmask legality" assignments's 8 networks to determine which were good and which were bad (so now, you don't have to do it yourself). Our result was that the bad ones are networks 2, 4, and 6 while the other five are good. Although you can thus answer the questions in the assignment without needing to do any hands-on activity, you might like to boot up your CLIENT or SERVER VM from the previous assignment and attempt to specify networks to the route command, the same ones that I did or others you test experimentally to see what you can learn. (3/13)

Homework - 
see/do - the homework column of course outline, section 5 ("netmask legality"). due on sputnik in the "assignments" subdirectory of your home directory end-of-day Thursday 3/18 
read, specifically -
the write-up at the link entitled "Masks, routing, and subnets" in course outline section 7
view - videos in course outline section 4 homework column
read, generally - readings shown in the course outline and link entitled "Reading list, per chapter." The latter is what I want you to read, from the textbook, for the whole course. Read forward to succeeding sections to prepare for upcoming topics. I will not further specify which items to read when. Read them all, for the entire course, in concert with in-class coverage as we proceed. By now you should have done the readings for sections 1-4 in the course outline. From that point, keep going independently week by week.
anticipate - our next subject, for next week, the arp protocol (address resolution protocol). arp interrelates the addresses of the internet and ethernet protocols in networks that use both (all our common networks do). See course outline topic 5 readings. If you read before next week, next week's lecture will be clearer to you.
(3/13)

Routing - important formulations of the "route" command
Three kinds of routes can appear in a routing table: host route for a specified individual machine, network route for a specified grouping of them, default route as catch-all for everything (unspecified) else. Here are the four key linux command formulations by which you add such routes to a routing table. Though there are 3 kinds of routes, note that 4 command formulations appear. We mentioned the concept of gateways (machines other than the destination, to which you would send the destination's packets for forwarding).  That accounts for there being 2 network route formulations below. One is for the case where the routed-to network is the one you yourself are plugged into, the other for the case where that network is "foreign" or "elsewhere" to you.

Add route to a machine (host route):
  route add -host 192.168.4.2 eth0 
Add route to a group of machines (network route - local) 
  route add -net 192.168.4.0 netmask 255.255.255.0 eth0 
Add route to a group of machines (network route - gatewayed) 
  route add -net 192.168.5.0 netmask 255.255.255.0 gw 192.168.4.1 
Add route to "any and all" (default route) 
  route add default gw 192.168.4.1

Study these commands intently and try to internalize the semantic meaning they embody. (3/13)

Windows route command - differs in syntax and scope somewhat from the linux command of the same name. But it is kindred in spirit and operates on the very same internet protocol (though not the same coded implementation of it). The internet protocol is defined outside Microsoft and outside linux. Both Microsoft and linux programmers  have taken their hand to writing programs that do what the protocol defines. Including a "route" command to manipulate the protocol's route table. In Windows, open a command box and execute "route print" if you wish to see the route table. (3/13)

Small networks: sizes for some common netmasks:

Netmask: # of one bits: # of zero bits: Implied network size:
255.255.255.0  24 8 256 (254)
255.255.255.128 25 7 128 (126)
255.255.255.192 26 6 64 (62)
255.255.255.224 27 5 32 (30)
255.255.255.240 28 4 16 (14)
255.255.255.248 29 3 8 (6)
255.255.255.252 30 2 4 (2)

(3/13)

Lego project - make a router for your toy trains. (How is this an applicable analogy to the processing of frames within a computer router?) (3/13)

Wireshark, protocols, and people
--how many protocols does it support? - Apparently the number of protocols supported has reached about 3000.
--who pays these open-source people, anyway? - in most cases nobody. Open source is a labor of love and mostly programmers don't get paid. As for who they are in the case of Wireshark, a list of "contributors" appears at the bottom of the Wireshark man page (that means "manual" page, the traditional form of unix/linux documentation-- give the command "man wireshark" on a linux computer to see it). To my surprise it lists about 1300 people. (3/13)

Grades - have been published, link entitled "Grade information" at left. They include the "ethernet frames," exercise plus 3 students' wireshark sniffing exercises submitted in the last couple of days.. Please call any anomalies to my attention. (3/12)

Grades - have been published, link entitled "Grade information" at left. They include the wireshark sniffing exercise. Please call any anomalies to my attention. (3/10)

Grades - have been published, link entitled "Grade information" at left. They include only the initial wireshark screenshot assignment. Please call any anomalies to my attention. (3/6)

Homework - 
view and listen - to the several video and audio links in course outline section 4 homework column.
view, listen, read - about undersea cabling at the several links in the post below.
read
- get started, readings shown in the course outline through section 4; also read forward to succeeding sections as you have time, to prepare for upcoming topics.
do - the "ethernet frames" assignment in course outline section 4 homework column.
due on sputnik in the "assignments" subdirectory of your home directory end-of-day Thursday 3/11 (3/6)

Undersea cabling - former student Philip Postovoit did the service of researching cabling quite thoroughly. Of the many links about it he sent me, I found particularly interesting:
submarine cable map (click individual cables)
manufacture, shipboard loading, seabed laying youtube video
Haut debit en eau profonde (French)
Transatlantic data cable by Microsoft/Facebook/Telexius completed.
"Contrary to conventional wisdom, satellites play a minimal role in the operation of the internet. Nearly 99% of international phone and data traffic goes through [submarine cables] like ours." Patricia Boulanger, Alcatel Submarine Networks 

Undersea fiberoptic cable landing point (Spain)

(3/6)

What other data link protocols besides ethernet are out there? You might instead have
  point-to-point protocol ("dial up")
  frame relay
  asynchronous transfer mode (ATM)
  802.11 ("wi-fi") in part (3/6)

What's the difference?
ARPANet, Leonard Kleinrock's network (now, the Internet), used dedicated connections between computer nodes. He made a phone call to Stanford from UCLA. The wire employed belonged to the phone company. The wire was not used by any other nodes, during the phone call. It was not shared. It was dedicated. Nodes that used it owned it and did not have to compete for it with any other nodes.
ALOHAnet, Norm Abrahamson's satellite based network among islands in Hawaii, used a satellite that could service only one connection at a time, and that all participating computer nodes had to use. So necessarily, nodes had to share it. It was non-dedicated. Nodes that used it did not own it and had to compete for it with all other nodes.
Ethernet was derived from ALOHAnet, and relied on a shared medium too. But while the ALOHAnet medium was radio to the satellite, the ethernet medium was a copper wire. (3/6)

Sunday office hours - we will hold an office hours zoom meeting at 3pm tomorrow Sunday, February 28. The main purpose will be to get students' VirtualBox installations and virtual machine importations done successfully. It's optional. It will be for students in both my CS40 and CS70 classes. Therefore this will be a different Zoom meeting than usual, and you won't join it the same way you join your class. Rather, please use this link instead:

https://cccconfer.zoom.us/j/98868349116?pwd=alc4alZ0Yy91TjBxOFhOQ2hFajlPdz09
Password: 960270
 (2/27)

Homework
upload - for homework this past week you made a screenshot of Wireshark after it had captured some network traffic. Please upload that file to the "assignments" directory under your home directory on the remote server, using your remote Unix system account. (This is how you will routinely submit homework.) due on sputnik in the "assignments" subdirectory of your home directory end-of-day Monday, March 1
do - the exercise at the link on the course outline's section 3 entitled "wireshark" It is labeled as "in-class exercise" but becomes homework you will do outside of class.
When you perform it the result will be 3 screenshot files that you produce in the course of performing the exercise:

statistics-udp.jpg (or .png)
statistics-tcp.jpg
exposed.jpg

I ask you to place these into a zip file named "wireshark-homework.zip" and upload it to your assignments directory. (Please ignore the questions you will see at the bottom of the assignment page. They are not for you. I only want the screenshots.) due on sputnik in the "assignments" subdirectory of your home directory end-of-day Tuesday, March 9  (2/27)

RFC process - how protocols get created. Here is a current example, HTTP 2 which was published as an RFC in May, 2015. See in particular the development timeline that has led it to this point. (2/27)

Screenshot of Microsoft Network Monitor. Compare the interface with Wireshark's. It demonstrates the product category (network "sniffers") to which both products belong.

Screenshot, Microsoft's Network Monitor sniffer

(2/27)

Dates and deadlines - I can be a little more specific than I was in class:
Class Census Day: MAR 2, 2021
Class 60% Day: APR 29, 2021
Last Day to Withdraw to Receive a Refund: FEB 28, 2021
Last Day to Withdraw to Avoid a "W": FEB 28, 2021
Last Day to Withdraw to Guarantee a "W": MAY 15, 2021
Last Day to Request for Pass/No Pass Grade: MAR 20, 2021

(2/21)

NASA Perseverence Mars rover landing last Thursday. NASA YouTube channel

Operating systems used by mission components:
VxWorks (Rover and Landing Visualization System)
RTEMS (Electra radios)
linux (Ingenuity helicopter)
none -TDS Landing Radar software, MOXIE Mars Oxidation In-situ Experiment

according to email message from JPL's Dj Byrne.

...and make success happen

(2/20)

Homework - 
1) read all the announcements below and follow all the links they contain. I will expect you to be familiar with the information they convey.
2) do the reading and homework shown in the "Reading" and "Homework" columns of the course outline's topic #1.  (2/20)
3) make progress in installing VirtualBox on your computer, and my delivered VM in VirtualBox (see link below entitled "Obtaining and installing". (2/22)

Course outline - with rough weekly topic coverage corresponded to related readings, homework assignments, and in-class slides I will use. Please follow this outline as we move through the topics, for assignments and reading I want to assign.

A virtual machine (VM) for you - hands-on lab exercises will be performed on a virtual machine that you can run in your own computer.
- Obtaining and installing your VM
- Transferring files in and out of it if necessary (accompanying howto video)
- Your VM's configuration
- VirtualBox networking "complete guide" - a good website on the subject

A Remote Unix system account is available for your use.

Using ssh (secure shell). ssh is an important tool you will use for interacting with remote computers. For that you will need an ssh client. There are a number of ssh client alternatives.

Distributing files from sputnik to the class as a whole,  publicly - the above file transfer discussion describes file movement to and from your own home directory, exclusive to you. Sometimes I will want to have someplace to put a file so everybody can get to it and download it. When I do that, here's how to download them.

Cover art on Tannenbaum textbook:

Networking textbook cover graphic

What is it??

"Number please?" asks the switchboard operator. The switchboard is a board. It's for switching. Switching changes a circuit between you and somebody. It can complete a circuit to your Aunt Bheulah in Iowa City so you can thank her for the knit socks. After you hang up if you want to call your uncle in Waco you'll need to switch circuits, to get a circuit to him instead of her. That's what the operator does for you. The "switch"ing in "switch"board is circuit switching. Nowadays in computer networks it's not circuit switching anymore, it's packet switching.

Phone swithboard operators c. 1950s

 

Functional layering - the famous "Open Systems Interconnect" model is depicted below. Somebody once had the idea that maybe there could be a way to get independent computer systems of different types to be able to exchange information with one another. The diagram blueprints the idea for "how in the world are we going to make that work??" That idea is the subject of this course.

The 7 layers of the OSI model

First-day administrative information you will need to know:

Running linux at home.

Slides available online - for most if not all slides I will show in class. Links to them can be found in the "Slides" column of the course outline.

Course-long textbook reading - a chapter-by-chapter list ( 6th edition, 5th edition ). The textbook is divided into chapters and they in turn into numbered sections. The list tells you which sections to read for this course when chapters are assigned. For example if I assigned chapter 10 and it had 17 sections, if this list specifies "10.1-100.5, 10.7, 10.12-17" it means I didn't feel sections 10.6 nor 10.8-11 were relevant enough so I only list the balance of the chapter. Read unlisted portions for your own interest if you wish, but the listed sections are what's officially assigned to you.

Textbook - Computer Networks and Internets, sixth edition, Douglas Comer, Pearson Prentice Hall , 2015.

Wireshark - is an excellent free packet capture utility. What is a packet, and why caputre it? We'll talk about that later. I will ask you to install and use Wireshark later in the semester, assuming you have a linux or windows computer available on which to do so. Please visit Wireshark's home page.

 

 

 

First message by telegraph 1844

"What hath God wrought?"
May 24, 1844

First message by telephone 1876

"Mr. Watson come here, I want to see you."
March 10, 1876

First message by internet 1969

"lo"
October 29, 1969