Prof. Choong Seon HONG

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Local Area Networks

• Prof. Choong Seon HONG

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12? ??? ???(LAN)

• 12.1 ???? (Project) 802
• 12.2 ???(Ethernet)
• 12.3 ?? ??(Token Bus)
• 12.4 ?? ?(Token Ring)
• 12.5 FDDI (Fiber Distributed Data Interface)

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??? ???(??)

• ??????(LAN)
• ??? ???? ??(???, ??, ?? ?)? ?? ???? ?? ???? ???
  ???? ??? ?? ???
• LAN? ??
• ???(Ethernet)
• ?? ??(Token Bus)
• ?? ?(Token Ring)
• FDDI(Fiber Distributed Data Interface) ANSI and
  ITU-T ???
• Data Link Control of LAN are based on HDLC

IEEE ???? 802 ???
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12.1 ???? 802

• IEEE ??? ????(1985? ??)
• ???? 802? OSI???? ??

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???? 802 (Contd)

• ???? 802

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???? 802 (Contd)

• IEEE 802.1
• LAN? ?????? ?? ?
• ?? ??????, ??? ? ?? ?? ????? ???? ?? ???? ??
  (architecture) ?? ???? (incompatibility) ? ??
• LLC(Logical Link Control)
• IEEE 802.2
• ???????? ?????? ?? LAN ????? ??
• Containing the synchronization, flag, flow, and
  error control specifications
• MAC(Medium Access Control)
• ????? ??? ?? ?? ???? ?? ?????? ??

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???? 802 (Contd)

• ???? ??? ??(PDU Protocol Data Unit)
• LLC ?? ??? ??
• HDLC? ??? 4?? ??? ??

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???? 802(??)

• ??(Control) ??
• HDLC? ?? ??? ??

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12.2 ???(Ethernet)

• Xerox ??? ??? 802.3 ??
• Extended by DEC, Intel, and Xerox
• IEEE 802.3

(PSK)
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???(??)

• ACCESS Method CSMA/CD
• Today the terms Ethernet, CSMA/CD, 802.3 are
  used interchangeably

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???(??)

• Collision in CSMA/CD

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???(??)

• ????
• ??? ?????? ? Station (pc, workstation, print ?)
  ? ??? NIC(Network Interface card)? ??
• 6??? ??? ??? ?? ??

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???(??)

• ?? ??
• ?? ??(Signaling)
• ?????(Baseband)??? - Manchester digital Encoding
• ?????(Broadband)??? - differential PSK
• ????(data rate)
• 1100Mbps

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???(??)

• ??? ??( Frame Format)
• Not providing any mechanism for acknowledging
  received

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???(??)

• ?????
• Preamble(7???) combined the alert, timing,
  start synchronization
• SFD(Start frame delimiter) - ??? ??
• the everything that follows is data.
• DA(Destination address) - ??? ??
• SA(Source address) - ??? ??
• PDU ??/??
• 802.2 ???(PDU) - 461500 ?????
• CRC - ?? ?? ??, CRC-32

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???(??)

• ??(Implementation)
• 10BASE5 Thick Ethernet
• 10BASE2 Thin Ethernet
• 10BASE-T Twisted-pair Ethernet
• 1BASE5 Star LAN
• Fast Ethernet

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???(??)

• 10BASE5 Thick Ethernet(???)

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???(??)

• 10BASE5 Thick Ethernet
• RG-8 ??? 802.3 ?? backbone thick ?????
• ????(transceiver) MAU(medium attachment unit),
  transmitter-receiver
• AUI(attachment unit interface) ???
  15-wire???(DB-15pin),???? 50m
• ???? ?(Transceiver Tap) vampire tap

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???(??)

• ??? ????

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???(??)

• 10BASE5 ???? ??

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???(??)

• 10BASE2 Thin Ethernet
• NIC - thick Ethernet NIC transceiver
• Thin ????? - RG-58
• BNC-T - T?? ???(3ports NIC, input, output)

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???(??)

• 10BASE2 Thin Ethernet(???)

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???(??)

• 10BASE-T Twisted-pair Ethernet
• The most popular standard defined in the IEEE
  802.3 series
• Star?
• UTP(Unshielded twisted pair) ???
• ???? 10 Mbps
• ???? 100M(hub to station)
• Intelligent hub ??
• Four-pair RJ-45 ???

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???(??)

• 10BASE-T Twisted-pair Ethernet(star?)

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???(??)

• 1BASE5 Star LAN
• ATT??
• ?? ???? 1 Mbps
• Twisted-pair ???
• Hub? ?? 10station

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???(??)

• 1BASE5 Star LAN

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12.3 Other Ethernet Networks

• An Ethernet network using a hub

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Other Ethernet Networks (contd)

• An Ethernet Network Using a Switch

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Other Ethernet Networks (contd)

• Fast Ethernet
• ?? ???? 100Mbps
• Star?
• 10base-T? ?? MAC ????? ??? ??
• 4pair category3, category5 UTP (2 pairs for
  transmission and two pairs for reception)
• 100BASE-X 2pair high-quality category5
• 100BASE-FX two optical fiber
• 100BASE-TX 2pair STP

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Other Ethernet Networks (contd)

• Categories of Fast Ethernet Implementations

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Other Ethernet Networks (contd)

• 100Base-Tx Implementation

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Other Ethernet Networks (contd)

• 100 Base-Fx

The distance between the station and hub (or
switch) should be less than 2000 meters
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Other Ethernet Networks (contd)

• 100Base-T4 Implementation
• Using four pairs of category 3 (voice grade) UTP
• splitting the 100-Mbps flow of data into three
  33.66-Mbps flows
• Using 8B/6T
• Eight bits is transformed into six bauds of
  three voltage levels (positive, negative, and
  zero)

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Other Ethernet Networks (contd)

• 100Base-T4 Implementation (contd)

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Other Ethernet Networks (contd)

• Gigabit Ethernet
• 1000 bps 1 Gbps
• MAC layer and access method remain same, but the
  collision domain is reduced
• Physical layer transmission media and the
  encoding system is changed
• Used for backbone to connect Fast Ethernet
  networks

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Other Ethernet Networks (contd)

• Use of Gigabit Ethernet

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Other Ethernet Networks (contd)

• Comparison between the Gigabit Ethernet
  Implementation

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12.4 ?? ??(Token Bus)

• IEEE 820.4
• ?????? ???
• Physical Configuration of Ethernet
• ????? ??? ??? ??(Ring using token)
• Using the collision-free feature of token ring
• ?? ???? ???? ??? ??

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12.5 ?? ?(Token Ring)

• IEEE 802.5
• token passing ?? access method
• Using three-byte token
• token possession
• Token ring allows each station to send one frame
  per turn.

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?? ?(??)
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?? ?(??)

• ?? ?
• ????(Priority)? ??(Reservation)
• use of access control (AC) field
• ????(Time Limit) 10ms
• each station expects to receive frames within
  regular time intervals
• ??(monitor) station
• Monitoring, regenerating a new token
• ??
• 6 ??? ?? (imprinted on the NIC card)

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?? ?(??)

• ?? ??
• differential Manchester ???????
• ???? 4-16Mbps
• ?????
• ???(data)
• ??(token)
• ??(abort)

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?? ?(??)

• ?? ? ???

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?? ?(??)

• ??? ??? ???

For Differential Manchester
Error Detected Bit
Control information or Data
How to use the information in the AC field
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?? ?(??)

• ?? ? ???
• SD (Start delimiter) ?? ??? ??
• used to alert the receiving station to the
  arrival of a frame
• equivalent to the flag field in HDLC
• adopted J and K violation to ensure
  transparency in the data field
• AC (Access control) ????
• Three bits priority field
• the token bit set to indicate that the frame
  is a data frame rather than a token or an abort
  frame
• FC (Frame control) ????(??, ???)
• the first one bit used to indicate the type
  of information contained in the PDU (control
  information or data)
• 7 bits containing information used by the
  token ring logic (e.g., how to use the
  information in the AC field)

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?? ?(??)

• DA(Destination address)
• SA(Source address)
• Data4500???
• CRCCRC-32 ?? ??
• ED(end delimiter)
• FS(Frame status) ???? ?? ??
• set by the receiver to indicate that the frame
  has been read, or by the monitor to indicate that
  the frame has been already been around the ring
• So, saying that the frame can now be discarded

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?? ?(??)

• ?? ???
• 3?? ??? ?? SD, AC, ED
• used as a reservation frame to serve access to
  the ring
• ??(Abort) ???
• ?? ??
• Just including SD and ED
• generated either by the sender to stop its own
  transmission, or by the monitor to purge an old
  transmission from the line

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?? ?(??)

• Implementation
• The ring in the Token Ring consists of a series
  of 150-ohm, STP sections linking each station to
  its immediate neighbors

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?? ?(??)

• Token ring Switch

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?? ?(??)

• MAU(Multistation Access Unit)

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12.5 FDDI (Fiber Distributed Data Interface)

• ANSI? ITU-U(ITU-TX.3) ??
• ???? ????
• Copper version of FDDI CDDI
• ???? 100Mbps
• FDDI ??

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FDDI (contd)

• Access Method Token Passing
• access is limited by allotted time
• Each station has three Time Registers to control
  circulation of the token and distribute link
  access opportunities among the nodes equitably.
• Values are set when the ring is initialized and
  do not vary in the course of operation
• SA (Synchronous Allocation)
• The length of time allowed each station for
  sending synchronization data (time sensitive
  data)
• The time value is different for each station and
  is negotiated during initialization of the ring

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FDDI (contd)

• TTRT (Target Token Rotation Time)
• The average time required for a token to
  circulate around ring
• AMT (Absolute Maximum Time)
• A value equal to twice the TTRT
• If a token takes longer than this time to make
  one rotation of the ring, the ring must be
  reinitialized.
• Timers
• Token Rotation Timer (TRT)
• The actual time taken by the token to complete a
  cycle
• Token Holding Timer (THT)
• Begins running as soon as the token is received
• Showing how much time remains for sending
  asynchronous frames

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FDDI (contd)

• Station Procedure
• When a token arrives, each station follows this
  procedure
• THT is set the difference between TTRT and TRT
  (THT TTRT TRT)
• TRT is reset to zero (TRT 0)
• The station is set to zero (TRT 0)
• The station sends asynchronous data as long as
  the value of THT is positive.

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FDDI (Contd)
2

• FDDI Example

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FDDI (Contd)

• Addressing
• six-byte address similar to Ethernet address
• Electronic Specification
• Signaling (physical layer)
• using a special encoding mechanism called 4B/5B
• encoding by NRZ-I
• Data Rate
• up to 100 Mbps

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FDDI (Contd)

• Encoding by NRZ-I

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FDDI(??)

• FDDI ????

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FDDI(??)

• FDDI ??? ??

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FDDI(??)

• FDDI ?(Dual Ring)

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FDDI(??)

• FDDI ? ??
• The secondary ring makes FDDI self-healing.

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FDDI(??)

• Nodes
• ?? ???(DAS dual attachment station)
• 2?? ?? ????? ???(MIC media interface
  connector)? ???? 2?? ?? ??
• ?? ???(SAS single attachment station)
• ??? MIC? ??? ??? ?? ??
• ?? ????, ??, ?? ??? ?? MIC? ??? ??
• ?? ?? ???(DAC dual attachment concentrator)
• ?? ?? SAS ??
• ?? ?? ??

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FDDI(??)

• Node connections

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12.6 LAN ??