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3COM SuperStack 2 10/100 Baseline Switch 3C16465A

3COM SuperStack 2 10/100 Baseline Switch 3C16465A. Naomi Avigdor October 25, 2001. CSMA/CD. Carrier Sense Multiple Access with Collision Detection Bus topology – shared media Half Duplex - CSMA/CD states Idle Transmission

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3COM SuperStack 2 10/100 Baseline Switch 3C16465A

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  1. 3COM SuperStack 210/100 Baseline Switch3C16465A Naomi Avigdor October 25, 2001

  2. CSMA/CD • Carrier Sense Multiple Access with Collision Detection • Bus topology – shared media • Half Duplex - CSMA/CD states • Idle • Transmission • Contention: if no collision occurs before the end of the period, then complete transmission of the frame

  3. Half Duplex MAC (think conference call) • CS – Carrier Sense (Is someone already talking?) • If not – then transmit if you have data • If yes - wait • MA – Multiple Access (everyone hears everyone) • Jim: “Hey Scott, This is Jim, what is the weather in Chicago?” • Tony: “Hey Susan, This is Tony, would you marry me?” • CD – We are both talking • “everybody stop, we have a collision”

  4. Collision Domain • Twice the maximum network end to end propagation delay • Defines Network diameter • Defines minimum frame size

  5. Full Duplex – Ethernet Switch • UTP – Unshielded twisted pair • Transmit pair separate from receive pair • Point-To-Point only • Media not shared, no collision domain • Aggregate throughput is doubled • Transmit and receive simultaneously • Each switch port own MAC

  6. Switch Internals • Shared RAM • “Store & Forward” or “Cut Through” • Input queuing versus Output queuing • Head-of-Line (HOL) blocking • Scheduling: • Port priority • Round Robin • Global FIFO

  7. Individual Switch Write Performance

  8. Aggregate Switch Write Performance

  9. Flow Control • Ok to mix port speed • Use MAC “Pause Frame” for flow control

  10. Channel Bonding • Network Interface Cards (NICs) bonded for outgoing load balancing • Does it bond for incoming traffic???

  11. References • http://www.iol.unh.edu/training/ge/Ethernet_Evolution_files/frame.htm • IEEE 802.3 standards doc. • Computer Networks Third Ed.by Andrew S. Tanenbaum

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