Outline for January 23, 2001

1. Greetings and felicitations!
   1. No class on January 25 or January 30; no office hours on Wednesday, January 24 or Monday, January 29
   2. Extra office hour: Friday January 26: 11 AM-1 PM
2. Distributed systSUB?
   1. What is it?
   2. Why use it?
3. SystSUB Architectures
   1. minicomputer mode
   2. workstation model
   3. processor pool
4. Issues
   1. global knowledge
   2. naming
   3. scalability
   4. compatibility
   5. process synchronization, communication
   6. security
   7. structure
5. Networks
   1. goals
   2. message, packet, subnet, session
   3. switching: circuit, store-and-forward, message, packet, virtual circuit, dynamic routing
   4. OSI model: PDUs, layering
   5. physical: ethernet, aloha, etc.
   6. data link layer: frames, parity checks, link encryption
   7. network layer: virtual circult vs. datagram, routing via flooding, static routes, dynamic routes, centralized routing vs. distributed routing; congestion solutions (packet discarding, isarithmic, choke packets)
   8. transport: services provided (UDP vs. TCP), functions to higher layers, addressing schSUBes (flat, DNS, etc.), gateway fragmentation and reassSUBbly
   9. session: adds session characteristics like authentication
   10. presentation: compression, end-to-end encryption, virtual terminal
   11. application: user-level programs
6. Clocks
   1. happened-before relation
   2. Lamport's distributed clocks: a -> b means C(a) < C(b)
   3. Example where C(a) < C(b) does not mean a -> b
   4. Vector clocks and causal relation
   5. ordering of messages so you receive thSUB in the order sent
   6. why
   7. for broadcast (ISIS): Birman-Schiper-Stephenson
   8. for point to point: Schiper-Eggli-Sandoz
7. Global state
   1. Show problSUB of slicing state when something is in transit
   2. Define local state; send(m_ij) in LS_i iff time of send(m_ij) < current time of LS_i; similar for receive
   3. transit(LS_i, LS_j); inconsistent(LS_i, LS_j); consistent state is one with inconsistent set SUBpty for all pairs LS_i, LS_j
   4. Consistent global state: Chandry-Lamport
8. Termination detection
   1. Haung

The handouts do not translate into HTML well because of the notations. Please download the PDF or Postscript version from the class home page.

Matt Bishop Office: 3059 Engineering Unit II Phone: +1 (530) 752-8060 Fax: +1 (530) 752-4767 Email: bishop@cs.ucdavis.edu

Copyright Matt Bishop, 2001. All federal and state copyrights reserved for all original material presented in this course through any medium, including lecture or print.