INFS 750: Last Class Meeting!

Exam up tonight! Due Thurs. 11:55 p.m.

• Remember: you get 2 hours!
• Penalty per word over 150 per essay!

Panko, Chapter 11: Network Applications

Users care about applications. The rest is a black box they don’t want or need to open.

1950s-60s: apps hosted by mainframes that did all the work, dumb terminals connected (usu. via coax-style cable, but some by modem-telephonenetwork-modem). No intergrated circuit CPU until 1971 (Intel! the 4004 4-bit microprocessor); all done by vacuum tubes (when “bugs” in the system meant bugs in the system: moths came to the light emitted!). Slow response time, monochrome text, graphics rare, transmission expensive.

1981: first IBM PC used Intel 8088 8-bit CPU

Client/Server Computing: the terminal does at least some processing. Remember: today’s laptops can run the Space Shuttle. Servers are still faster.

Filtering e-mail out of your server is really important if you’re in one of the industries that regs require to archive all e-mail for seven years! Several apps can help with that process.

E-mail protocols:

1. SMTP (Simple Mail Transfer Protocol): sender-initiated
2. POP or IMAP to download; receiver initiates

Separate E-mail Body Standards for all-text, HTML…

NetAdmins need to worry more about viruses, worms, Trojan horses, spam, spyware, etc. Widespread problems; antivirus software is almost universal and generally ineffective

1. So outsource to Postini! Even if you still maintain your own firewall, two lines of defense are better than one.

Spam is bad:

1. consumes bandwidth
2. consumes network staff time
3. consumes user time
4. may trigger sexual harassment suit (hostile environment! network admin has responsibility not to let such garbage into the workplace!)
5. consumes storage space if regs require archiving of all e-mails

E-Commerce: Internet opened to it in 1991 (come on, almost 20 years: we should have it figured out by now! ;-) )

• started with online catalogs
• then shopping cart, checkout, payment
• customer resource management (CRM)
• links to external systems
• links to internal systems (accounting, pricing, warehousing, shipment, etc.: go check out eBay!)

Peer-to-Peer Computing:

• Gehl investigated using this model to distribute user manuals and other docs so they wouldn’t have to upgrade a file server
• method avoids overload of central server
• also avoids single point of failure
• gives end user more freedom
• uses client capacity better
• Problem: clients come and go (switched off for night!)
• Problem: client IP addresses switch!
• Biggest Problem: sceurity! no central control!
• grad student at research symposium last week talked about working up a model on using P2P capacity in Mayo Clinic to analyze med data
• Pure P2P IM has no servers, but finding each other can be a hassle if you restart your computer and get a new IP

 

South Dakota: One Big Hotspot

South Dakota, Wireless Hotspot: Feasibility of Statewide WiMAX-Enabled Municipal Internet Built on the K-12 Network

A paper submitted 2009.04.13
for INFS 750 Networks (etc.)
By Cory Allen Heidelberger

ABSTRACT

Municipal wireless Internet offers potential economic and cultural benefits to all communities. However, the capital (physical and human) required to deploy and manage such networks appears to set a natural lower bound on the size of community that can successfully sustain such a system. Rural communities in South Dakota, most with populations under 10,000, likely fall below that threshold. Therefore, this paper proposes a model for a statewide cooperative network of municipal wireless Internet services in South Dakota, built on the existing infrastructure that provides Internet access to public schools across the state.

 

INFS 750: Class Meeting!

Hey! Don’t forget to do the quiz on D2L before April 15! It will be over the CSI 2008 slideshow PDF.

APA Bib: single-space refs, hanging indent, leave double space between entries.

Mark also said we need not use all-caps for headings. He doesn’t like the shouting.

Table titles go on top; figure titles go on bottom!

 

INFS 750 — Lecture Notes — March 19

Spring break’s over — back to work!

On the big paper:

• Dr. Moran is using EVE to check for plagiarism.
• 8-12 pages double spaced, not counting title, bib, etc.

Hey! Ethics is coming up… next time (drat!).

TCP/IP

(remember: for the final, you will be asked about the 4 ways to identify a computer on the network [MAC, port, IP, name], Ethernet, and TCP/IP. Mark will ask for compare and contrast of TCP and UDP: see p. 310 among others… and be ready for questions that you have to think about, not questions that you will look have to look up)

Again, Panko makes a big deal about the difference between packets and frames. Mark and Jeff both say that difference never comes up in practice

Again, the five layers:

1. Physical (none: use OSI standards)
2. Data Link (none: use OSI standards)
3. Internet (IP, ICMP, ARP)
4. Transport (TCP, UDP)
5. Application (HTTP, SMTP, DNS, Dynamic Routing Protocols, etc.)

Switches are faster because they know the MAC addresses, which don’t change.

Routers look at IP addresses, which can change.

There’s no way to look at an IP and determine the network, subnet and host parts, just their total of 32 bits. Masks solve this problem:

• mask: series of initial ones followed by a series of final zeroes for a total of 32 bits.
• use ipconfig /all to find mask
• the subnet mask tells you how many addresses you have available (ask a gearhead)

Routing: processing an individual packet and sending it

Routing table: used to make routing decisions (switches don’t need this: they just fire things out to the given MAC address, no changing, no deciding)
–each row represents a route
–router goes through the table, pulls matching destinations, then figures out the best route (kind of like how we navigate around Sioux Falls)
–routing decisions are constantly updated based on traffic: they can tell which of their neighbors are really busy with various tasks and route away from them
–best match criteria: longest match (initial 1s) in row mask, lowest cost, highest speed

Address Resolution Protocol (ARP): this is how routers find out MAC addresses (the data link layer address! we’re stepping down from Layer 3 [Internet] to Layer 2 [data link])
–broadcasts to all routers nearby the destination requesting MAC: the router that knows responds, others ignore.

Internet Protocol (IP) versions 4 and 6: IPv4 is what we started here in the U.S.; IPv6 is taking off elsewhere since we hogged all the IPv4 addresses.

IPv4 is 32-bit (2^32 = 4.3B); packet includes a time-to-live value (usu. 64 or 128) that each router decreases by 1 — when that bit hits zero, the router drops the packet, since it’s taking too long to get to destination, and we don’t want packets bouncing around the Internet all day.

[Remember that Bill Gates didn’t realize the Internet was big until 1997.]

IPv6 is 128-bit (2^128 = 3.4*10^38). We should have enough addresses for some time. Atoms in Earth: 8.87*10^49. Atoms in human body: 7*10^27.

DHCP: Dynamic Host Configuration Protocol: they’ll do a lot of this in INFS 752 this summer! Clients get dynamic IP addresses. You want servers and routers to have static IPs, but workstations can be dynamic, thus freeing us of the administrative effort to assign IPs to each machine (nice in case there’s a problem)

Why DHCP? [there’s a good essay question!] entering IPs manually is a high-cost task (see Panko, p. 338)

IP not reliable, no guarantees

The three-way handshake happens with any TCP/IP connection: SYNchronization, SYN/ACKnowledgment, ACK.

Normal four-way close: FIN, ACK, FIN, ACK. (Each server says FIN, each ACKs.)

There are 65535 possible ports:

• Port 80 = Internet
• Port 25 = e-mail
• Ports 0 to 1023 used for both TCP and UDP
• Ports 1024 to 4999: “Ephemeral Ports” for Windows Client PCs
  • each program on the client gets a different port

Socket = IP:port (e.g. 128.171.17.13:2849 represents an app on that particular server)

Dynamic Routing Protocols: routing tables that change!

Layer 3 switches are faster, less expensive.

TCP is a heavyweight protocol because it has sequence numbers (number for each packet to allow reassembly of packets at destination; they can arrive out of order!), it is reliable (each segment is ACKnowledged by receiver — but note that TCP will set window size based on the quality of the connection: if the connection is going well, it may ask for ACK for every 5, 10, 80, 500 packets; if too many are dropping, TCP will shrink the window and ask for more ACKs)

Note that TCP sequence numbers don’t start at 1 — they start with random numbers (though algorithms exist to determine the initial sequence number)

One TCP segment may have multiple data chunks; supervisory segments carry no data, are treated as a single octet

TCP Fragmentation: TCP segments have maximum data field sizes! if the application-layer message is too big, TCP breaks it up into separate segments.

Maximum Segment Size: default is 536 octets, can vary if each side (sender and receiver) issues an option in the initial SYN to accept larger MSS

Maximum Transmission Unit: largest IP packet that network will accept. If router receives a packet bigger than the MTU, the router will break the packet into fragments!

Routing Information Protocol: older, simplest, limited to 15 hops (not enough for D2L, which takes 20 hops), used only inside smaller networks. Converges slowly (i.e., takes a long time, maybe several minutes, to get a correct routing table after a failure of a router or link); uses UDP on Port 520

Open Shortest Path First Routing Protocol: much better! responds quickly to router failures, finds most efficient route quickly. Divided network into areas, sends routing table info only to associated routers in each area, not everyone in network; that managing router in each area handles notifying its area members — that helps make fast convergence. OSPF is scalable!

Border Gateway Protocol: most popular! (remember, gateway is old term for way to get from one network to another; that’s a router! not many people refer to gateways any more); uses distance vector approach.

IP addresses: get some class!
–you know it by the subnet mask: Class A has 8 bits (24 bits in local part); Class B has 16 bits (16 local); Class C has 24 bits (8 local)

Class A starts with 0 (binary!), Class B 10, Class C 110

• A: 1-126 N.H.H.H
• B: 128-191 N.N.H.H
• C: 192-223 N.N.N.H
• D: 224-239
• E: 240-255

MultiProtocol Label Switching: very similar to virtual cricuits in ATM

 

Class Meeting #3: Ethernet, Wireless

95% of networks are Ethernet

Early history:

• developed at Xerox Palo Alto by Metcalfe and Boggs
• standardized by Xerox, Intel, and Digital Equipment Corporation

 

Municipal Wireless Networks — opening articles

I’m putting together a paper on municipal wireless networks (Muni Wi-fi) for INFS 750. Here’s the first small batch of articles I tracked down for the annotated bibliograpjy assignment:

 

INFS 750: Class Meeting 2009.01.29

Slide Shows in D2L Content area — watch ’em!

Tonight’s plan:

1. Annotated Bib
2. Review network plan assignment
3. Writing in APA
4. Panko Ch. 2: Network Standards
5. Panko Ch. 3: Physical Layer

 

APA Style: Things to Remember!

I’m reading Purdue’s APA style tips, which Dr. Moran is all about in INFS 750. Here are some points that I need to pay special attention to, since either they diverge from my usual practice or I just have trouble remembering.

1. In text, capitalize titles! Not just the first word of the title (and subtitle), but everything, per standard cap rules, the way I like it! (But in Refs, only journals get full title caps.) However, Dr. Moran prefers full title caps everywhere, in clear contravention of APA, since most of the journals to which he submits prefer full title caps.
2. When capitalizing titles, capitalize all words four letters long or longer: Gone With the Wind.
3. Precede page refs with “p.”: Lowery (2008) has called on “all who do justice and love mercy” to “say Amen” (p. 2).
4. Commas if all together: (Lowery, 2008, p.2)
5. Blockquote trigger: more than 40 words.
6. In text three to five authors: identify all by name first time, then First et al.
7. Six or more authors: that’s too damn many authors anyway. Cite in text as First et al. every time.
8. Join two authors with and in text, ampersand in parenthetical cite.
9. Footnotes and endnotes are frowned upon, “because they are often expensive for publishers to reproduce.”
10. References: Do hanging indent! half-inch!
11. Do not capitalize second word in hyphenated compound.
12. No quote marks for article titles.
13. Magazines and Newspapers: Jones, B. (2008, October 4).
14. City: Publisher.
15. Online sources: Retrieved Month Day, Year, from URL.
16. Ditch he AND she for they. Just don’t even go there.
17. Only senior scholars get to use first person. (In other words, first person is for God and minor deities, not you.)
18. Active voice rules!
19. Don’t rhyme or alliterate (really!).

 

INFS 750: Semester Project Topics

[submitted via D2L to Dr. Moran, 2009.01.22]

So tell me if this will be a sufficiently meaty and relevant topic for class: I’d like to investigate municipal/community wireless networks. Aberdeen initiated a program last year to make their downtown one big public-access hotspot; it might be interesting to e-mail them (or even take a roadtrip!) to learn about their network and their experience with it. I could also add some background on the projects in San Francisco and Philadelphia, though I’d love to keep my focus on the feasiblity and advantages/disadvantages of such programs for rural South Dakota communities.

Municipal Wireless is my first choice, but if that doesn’t fulfill the requirements for the assignment, I do have a couple back-ups (rural broadband, impact of infrastructure stimulus; replacement of in-house networks with virtual/WiMAX). Let me know what works! Thanks!

 

INFS 750: First Lecture

First meeting of INFS 750: IT Infrastructure, Technology, Network, Management… the whole shootin’ match!

We open with a review of library research from Mary Francis of the Mundt Library

Research note: Dr. Moran declares Wikipedia an acceptable source for our papers! He notes that Wikipedia articles on network tech are generally above average (and quickly corrected).

Google Scholar is cool, but you can’t access a lot of the stuff without going to the Mundt databases anyway. Still, I’m of the impression the search capability of Google Scholar gets us to relevant titles more quickly. Then I can track down that specific article in the database and fan out to related material from there. Even in ABI/INFORM, if I start searching, I may get results that aren’t held in that database, requiring me to go use the Journal Finder to see if that title is available anywhere at DSU, just as I do after a Google Scholar search.

Oh! Check out this INFS/INFA 700-Level Research Guide!

• including this fun outline of the graduate student research process (funny, it doesn’t include Cheetos and Mountain Dew…)
• Mary says that computer science types might like having a nice step-by-step checklist for conducting research. Mark reminds her that we are information systems people: we’re more humanistic, less nerdy! That’s also why we use APA style instead of IEEE: to signify our inclination toward the humanities.
• Oh! See the Mundt’s very own style guides!
• By the way, Word 2007 will do APA etc. for you! And Mark says Word is good enough for him in this class.
• Big 3 infosys databases:
  • ABI/INFORM Complete (ProQuest)
  • ACM Digital Library
  • IEEE Computer Society Digital Library
• ethical use of information:
  • copyright is automatic! You don’t have to stamp a little © on your notes to make them your own…
  • …but give credit where credit is due! you should definitely make sure you give Mary Francis proper credit for the fine things she’s telling you about intellectual property!
  • citing sources gives proper credit, supports your text, and lets readers check your sources (see for yourself: so very bloggy)

——————————–

Lecture Part 2: Dr. Moran does the course intro

Our text is by Ray Panko! Mark is buds with him! Panko likes canoeing. (Panko also digs spreadsheet research.)

Early papers graded more on APA style, refs and such than content.

Expect about 100 points worth of work each two-week cycle. We have three assignments this first cycle:

1. Assignment 1 from the text
2. Network plan
3. Pick a Big Paper topic
   1. doesn’t need to be a big honking doctoral paper! just a knowledge paper! history, background, how-to… maybe even a position paper!
   2. Draft due in March

Assignments generally due the night before class!

TCP/IP is a big deal: you can’t come out of a networking class without knowing how TCP/IP works!

———————————-

Panko, Chapter 1: An Introduction to Networking

Four ways to identify a computer on a network:

1. Physical address (a.k.a. MAC: Media Access Control; doesn’t change unless you’re hacking to hide yourself)
2. IP address (changes a lot)
3. name (Microsoft likes that)
4. port (usu. stuck w. IP)

Network basic def: communication system that allows application programs on different hosts to work together

Host: anything attached to network; anything with an identifier

Application standards (a.k.a. protocols) govern communication between application programs

HTTP (Hypertext Transfer Protocol) standardizes communication between browsers (clients) and Web servers

• HTTP is an open standard (thank you, DoD)

ARPANet:

• created by Defense Advanced Research Projects Agency circa 1970
• served researchers doing business with DARPA
• connected several sites nationwide
• some of first networked apps created for ARPANet
• eventually became the Internet (1980)
• ARPANet evolved into Milnet (very secure, very paranoid)

Other early networks:

• CSNET in computer science
• BITNET in biz and soc sciences
• Ethernet: Xerox came up with it before APRANet, made it free (and thank goodness)

Internet:

• DARPA created 1980
• became commercial 1995
• 1996: Bill Gates gets serious about Internet
• almost no gov’t money keeping ‘Net afloat now

Traditional Internet Apps:

• File Transfer Protocol
• E-Mail
• World Wide Web
• E-Commerce

Internet is a global transmission system. WWW is an app!

Newer Internet Apps:

• Instant Messaging
• Streaming Audio/Video
• Voice over IP
• Peer-to-Peer Apps

[ITCTel runs fiber-optic to Lake Madison; Mark gets his TV over IP!]

Web 2.0, ERP (DSU does PeopleSoft/Oracle because USD got SAP, and SAP only works with one university per state)

Quality of Service:

• indicators of network performance
• this is really important! the network must work! people count on it like air!
• lots of diff metrics (speed, error rates, latency and jitter…)

Security:

• attacks can be costly
• ARPANet once had 4 nodes: who needed security?
• cryptographic protections
• shades of getting away from the bear: you at least want to be more secure than the other guys

Ethernet: switched networks!

• messages are called frames
• switched networks use MAC addresses (media access control) in hexadecimal!
• DSU: each building is its own domain, separate network; relatively small camppus-wide network with just a couple thousand computers
• core switch and workgroup switches

Routed networks use IP addresses (and those can change! that’s why routed networks are slower!

• routers have to be faster because they have to ask other routers where things are (smarter, take more processing time)

ISP subscriber payments finance the Internet

WANs, LANs, and PANs (personal area networks!)

• big distinction: go from LAN to WAN and you lose control of the delivery mechanism (gotta use Qwest, DDN,…)
• WANs and LANs all can be routed or switched

Network Management much more automated now

• When Mark started here, we had just 600+ students, but we had more network tech managers than we do now, since so much had to be done manually

Simple Network Management Protocol (SNMP):

• manages multiple devices from central location
• collects info about each managed device
• can sometimes reconfigure managed devices remotely

————————

Possible topics for Cory’s semester paper:

1. Community wireless networks (WiMAX impact)
2. rural broadband, impact of infrastructure stimulus
3. replacement of in-house networks with virtual/WiMAX