15441 TopDown Roundup

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15-441 Top-Down Roundup
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The Big Picture

• Consider a Web browser.
• Fetching a page from ETrade Bank
  https//www.etrade.com/
• How does this happen at every step along the
  process?

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Points To Cover

• Physical Lower layers concepts (signal to
  digital signal to bits to packets)
• Encoding (NRZ, Manchester, etc.)
• Link Framing. Media access. Error Control.
  Flow Control.
• CSMA/CD
• Exponential Backoff
• Collision detection and RTT, min pkt size

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Points 2

• Network layer End to end addressing
• Vs phys Repeaters, Vs link layer (bridges), vs
  app layer (gateways)
• IP
• Hierarchy and CIDR (why each?)
• Routing
• BGP (path v), OSPF (LS), RIP (DV) why?
• Where is each used? (Draw network map)

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Points 3

• BGP ASes IBGP Full mesh (why? Loops!)
• Route internally with IGP
• Remember the decision process a bit
• AS relationships Valley free (why?)
• Transit Peering
• NAT maybe throw into diagram
• Ref to IPv6 and why IPv6?

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Points 4

• DNS. Go through very brief ex.
• Hierarchy from root down. Caching (TTL)
• Recursive resolvers
• TCP
• Reliability, in-order, demux, cong. Ctl, stream
• Hows it work? ARQ, sliding Window, TCP
• Optimal window size? Bwrtt. Why?
• Three-way handshake
• Finding window AIMD
• Slow start

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Points 5

• Routers
• Queueing FIFO vs WFQ vs RED (maybe)
• Drop-tail (problems? Synch)
• Max-min fairness, token buckets, QoS
• Wireless
• Start diagram with wireless client _at_ home
• Problem? Non-congestive losses - TCP
• Fix Link-layer vs end-to-end (sack? Etc)
• Recall RTS/CTS and Exposed/Hidden Term?

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HTTP

• Stateless. Cookies.
• Caching and CDNs
• Expiration / ETags
• Why persistent connections, etc?
• What can / cant be cached? Why CDNs?
• SSL

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Big Pic 2 Skype

• Whats different between using Skype and fetching
  a web page?
• Other stuff DDoS and other security issues
• P2P