(chapter 01 ??? ?? ??? LAN)

1

• ??? ????
• PART 02 ????
• (chapter 01 ??? ?? ??? LAN)
• ???
• E-mail htlim_at_dongseo.ac.kr
• Home page http//kowon.dongseo.ac.kr/htlim

2
Chapter 01 ??? ?? ??? LAN

• ??
• 1.1.1 LAN? ??
• ???, ??, ?? ?? ?? ??? ???? ??? ?? ???
• ???? ????
• LAN? ??
• ??? ?? ??
• ?? ?? ?? 1Mbps ?? Mbps
• ??(broadcasting) ??? ?? ????
• ????? ???
• ?? ??? 10-8, WAN 10-5

3
Chapter 01 ??? ?? ??? LAN

• 1.1.2 IEEE? LAN ???
• ?? 1.1

4
Chapter 01 ??? ?? ??? LAN

• 1.1.3 LAN ???? ?? ??
• ?? 1.2 LAN
  ???? OSI ???? ??

LAN ???? OSI ???? ??
5
Chapter 01 ??? ?? ??? LAN

• LAN, MAN? ??
• OSI ??? ?? 12? ??
• MAC ???(Sublayer)
• ???? ?? ???? ?? ??
• LLC ???(Sublayer)
• LAN ??? ???? ?? ??? ??? ??? ??
• ???? LAN ??
• CSMA/CD (IEEE 802.3)
• Token Ring (IEEE 802.5)

6
Chapter 01 ??? ?? ??? LAN

• IEEE? LAN ?? ???
• IEEE 802.1 ???? ????? ? MAC ???
• IEEE 802.2 LLC(Logical Link Control)
• IEEE 802.3 CSMA/CD(Carrier Sense Multiple
  Access/Collision Detection)
• IEEE 802.4 ?? ??(Token Bus)
• IEEE 802.5 ?? ?(Token Ring)
• IEEE 802.6 MAN(Metropolitan Area Networks)
• IEEE 802.7 ??? LAN
• IEEE 802.8 ??? LAN
• IEEE 802.9 ?? ??? ?? ????
• IEEE 802.10 ??(Security)
• IEEE 802.11 ?? ????(Wireless Network)

7
Chapter 01 ??? ?? ??? LAN

• 1.1.4 ???? (Topologies)
• ??(star)? ??
• ??(bus)? ??
• ?(ring)? ??
• ??? ??

8
Chapter 01 ??? ?? ??? LAN

• ??(Topologies)

9
Chapter 01 ??? ?? ??? LAN

• LLC(Logical Link Control) ????
• LLC ???-???(LSAP)? ??? ????? ???? ??
• ? ?? ??? ??
• Unacknowledged connectionless service (??? ???
  ???)
• ??? ??
• ACK, ????, ???? ???? ??
• Connection-mode service (?? ???)
• ACK, ????, ???? ??
• Acknowledged connectionless service (?? ??? ???)

10
Chapter 01 ??? ?? ??? LAN

• ?? 1.4 LLC PDU ??

11
Chapter 01 ??? ?? ??? LAN

• MAC(Medium Access Control)????
• 1.3.1 CSMA/CD (Carrier-Sense Multiple Access with
  Collision Detection)
• IEEE 802.3 MAC
• ??? ??? LAN?? ?? ????? ??
• ?? ???(Ethernet)???? ?
• CSMA/CD ??? ??? ??? ? ?? ?? ????? ??? ?????? ???
  ????? ?? ???? ????? ??(contention)? ?? ?? ???? ??
• Collision ?? --gtbinary exponential backoff? ??

12
Chapter 01 ??? ?? ??? LAN
Time t0 A? ??? ?? Time t1 D ? ???
?? Time t2 D? ??? ??, ?? ?? Time t3
A? ?? ?? ?? ?? ?? ??

• ?? 1.5 CSMA/CD ? Collision ?

13
Chapter 01 ??? ?? ??? LAN

• ?? 1.6 IEEE 802.3 ??? ??

14
Chapter 01 ??? ?? ??? LAN

• CSMA/CD ??? ???? ?? ??? 90 ???? ?? ???? ??
• ???? ???? ??? ??? ????? ?? ???? ???? ??
• ??? ???? ? ??? ??? ??
• ?? ??? ????? ???? ????? ????? ??? LAN?? ?? ??
  ??? ??
• ????? ?? ???? ???
• ???? ??? ???? ???? ??

15
Chapter 01 ??? ?? ??? LAN

• Ethernet CSMA/CD ??

• A sense channel, if idle
• then
• transmit and monitor the channel
• If detect another transmission
• then
• abort and send jam signal
• update collisions
• delay as required by exponential backoff
  algorithm
• goto A
• else done with the frame set collisions to
  zero
• else wait until ongoing transmission is over and
  goto A

16
Chapter 01 ??? ?? ??? LAN

• Ethernet CSMA/CD (more)
• Jam Signal LAN?? ?? ?????? Collision
  ? ????? ??? ?
• 48 bits
• Exponential Backoff
• Goal ??? ??? ??? ??? ?? ??
• heavy load ? ?? ????? ?
• ??? collision 0,1?? k? ?? ??(delay)??? K x
  512 bit ????
• ??? collision 0,1,2,3?? k ??
• ??? collisions 0,1,2,3,4,,1023?? k ??

17
Chapter 01 ??? ?? ??? LAN

• IEEE 802.3 ????
• ???? ??
• STP(Shielded Twist Pair)
• UTP(Unshielded Twist Pair)
• ?? ???
• 10BASE2?? ?? ??(thin) ?? ???
• 10BASE5?? ??? ??(thick) ?????

18
Chapter 01 ??? ?? ??? LAN

• ? 1.1 IEEE 802.3 ?? ?? ??? ??

19
Chapter 01 ??? ?? ??? LAN

• ?? 1.7 ? ?? ????? ?? 10 BASE 5 LAN ??

20
Chapter 01 ??? ?? ??? LAN

• ?? ??

21
Chapter 01 ??? ?? ??? LAN

• ?? ?? ?? CSMA/CD ??(Ethernet)

22
Chapter 01 ??? ?? ??? LAN

• ??(Hub)
  Ethernet Interface Card

23
Chapter 01 ??? ?? ??? LAN

• 1.3.2 Token bus(?? ??)
• IEEE 802.4 MAC
• ??? ???? ??
• ?? ??? ???? ?? ???? ?? ???? ???? ??? ?? ?? ??? ??
  ??
• ???? ?(logical ring) ??
• ????? ??? ????? ???? ??
• ??? ?? ?? ???? ?? ????? ??? ??? ? ??? ??? ??

24
Chapter 01 ??? ?? ??? LAN

• ?? 1.8 ?? ??? ???? ?

25
Chapter 01 ??? ?? ??? LAN

• ?? 1.9 ??? ?? ??

26
Chapter 01 ??? ?? ??? LAN

• ??????(Internetworking)

27
Chapter 01 ??? ?? ??? LAN

• ????? ?? ??
• LAN-LAN
• LAN-WAN
• WAN-WAN
• LAN-WAN-LAN
• ?? 1.11
• ??
• ???(Repeater)
• CSU/DSU
• ??(Hub)
• ???(Bridge)
• ???(Router)
• ?????(Gateway)

28
Chapter 01 ??? ?? ??? LAN

• ???(Repeater)
• ?? ??
• ??? ?? ?? ? ?? ?? ??

29
Chapter 01 ??? ?? ??? LAN

• CSU/DSU
• ?? ???? ??
• DSU(Data Service Unit)
• ??
• ??? ?? ??? ??
• ?? ?? ?? ??
• CSU(Channel Service Unit)
• ??
• DSU? ?? ??
• ?? ?? ? ?? ?? ?? ??

30
Chapter 01 ??? ?? ??? LAN

• ???(Bridge)
• ?? ??? MAC ??
• - ??
• ??? ?? ??
• ?? ??? LAN ?? ??
• ??? ??(??, ???) ??
• - ??
• ??? ???? ???(Transparent Bridge)
• ?? ??? ???(Source Routing Bridge)

31
Chapter 01 ??? ?? ??? LAN

• ???(Router)
• - ?? ??, ?? ??, ???? ??
• - ??? ??

32
Chapter 01 ??? ?? ??? LAN

• ?????(Gateway)
• - ?? ??? ??
• ??? ??? ??
• - ??? ??

33
IEEE 802.11 Wireless LAN

• 802.11a
• 5-6 GHz range
• up to 54 Mbps
• 802.11g
• 2.4-5 GHz range
• up to 54 Mbps
• All use CSMA/CA for multiple access
• All have base-station and ad-hoc network versions

• 802.11b
• 2.4-5 GHz unlicensed radio spectrum
• up to 11 Mbps
• direct sequence spread spectrum (DSSS) in
  physical layer
• all hosts use same chipping code
• widely deployed, using base stations

34
Wireless Link Characteristics

• Differences from wired link .
• decreased signal strength radio signal
  attenuates as it propagates through matter (path
  loss)
• interference from other sources standardized
  wireless network frequencies (e.g., 2.4 GHz)
  shared by other devices (e.g., phone) devices
  (motors) interfere as well
• multipath propagation radio signal reflects off
  objects ground, arriving ad destination at
  slightly different times
• . make communication across (even a point to
  point) wireless link much more difficult

35
Chapter 01 ??? ?? ??? LAN

• IEEE 802.11 LAN
• IEEE 802.11 Wireless LAN
• wireless LANs mobile networking
• IEEE 802.11 standard
• MAC protocol
• unlicensed frequency spectrum 900Mhz, 2.4Ghz
• Basic Service Set (BSS) (cell ???? ?) ????
• wireless hosts
• access point (AP) base station
• Distribution system (DS) ? ?? ?? BSS? ??

36
Chapter 01 ??? ?? ??? LAN

• IEEE 802.11 MAC Protocol CSMA/CA
• 802.11 CSMA ??? sender
• - if DISF sec.?? channel?
  idle
• then ??? frame? ?? (no
  collision detection)
• -if channel? ???
  then binary backoff ???? ??
• 802.11 CSMA ??? receiver
• if received OK
• return ACK after SIFS
• 802.11 CSMA Protocol others
• NAV Network Allocation Vector
• 802.11 frame has transmission
• time field
• ?? ???? NAV ????
• access ??

37
Chapter 01 ??? ?? ??? LAN

• Ad Hoc Networks
• Ad hoc network ????? AP ?? ????? ??? ? ??.
• Applications
• laptop meeting in conference room, car
• interconnection of personal devices
• battlefield
• IETF MANET (Mobile Ad hoc Networks) working
  group

38
Chapter 01 ??? ?? ??? LAN

• CA(Collision Avoidance) RTS-CTS exchange
• CSMA/CA explicit channel reservation
• sender short RTS (request to send) ??
• receiver short CTS (clear to send)? ??
• CTS? ??? ??,
• notifying (possibly hidden) stations
• avoid hidden station collisions
• IEEE 802.11? ??? ??
• CSMA
• CSMA/CA reservations

39
Avoiding collisions (more)

• idea allow sender to reserve channel rather
  than random access of data frames avoid
  collisions of long data frames
• sender first transmits small request-to-send
  (RTS) packets to BS using CSMA
• RTSs may still collide with each other (but
  theyre short)
• BS broadcasts clear-to-send CTS in response to
  RTS
• RTS heard by all nodes
• sender transmits data frame
• other stations defer transmissions

Avoid data frame collisions completely using
small reservation packets!
40
Chapter 01 ??? ?? ??? LAN

• PPP(Point-to-Point Protocol)
• Point to Point Data Link Control
• one sender, one receiver, one link broadcast??
  ?? ??
• no Media Access Control
• no need for explicit MAC addressing
• e.g., dialup link, ISDN line
• popular point-to-point DLC protocols
• PPP (point-to-point protocol)
• HDLC High level data link control (Data link
  used to be considered high layer in protocol
  stack!

41
Chapter 01 ??? ?? ??? LAN

• PPP non-requirements (??? ??)
• no error correction/recovery
• no flow control
• out of order delivery OK
• no need to support multipoint links (e.g.,
  polling)
• Error recovery, flow control, data re-ordering
• 
  ?? ??? ??

42
Chapter 01 ??? ?? ??? LAN

• PPP Data Frame
• Flag delimiter (framing)
• Address does nothing (only one option)
• Control does nothing in the future possible
  multiple control fields
• Protocol ???? ????
• ( ? PPP-LCP, IP, IPCP ? )

43
Chapter 01 ??? ?? ??? LAN

• Byte Stuffing
• data transparency requirement ??? ??? flag
  pattern lt01111110gt?
• ??? ? ??? ?.
• Q is received lt01111110gt data or flag?
• Sender ? lt01111110gt data byte ?? ???
  lt01111110gt ??? ??
• Receiver
• ??? ???? lt01111110gt ?? ??? ??? ??, ??? ?? ??
• ?? 01111110 flag byte

44
Chapter 01 ??? ?? ??? LAN

• Byte Stuffing

45
Chapter 01 ??? ?? ??? LAN

• PPP ?? ???? (RFC 1557)
• packet framing ??? ?? ??? ?? ???? ?? ??????
• Encapsulation.
• bit transparency data ???? ??? ????? ???? (Byte
  Stuffing)
• ?? ??(?? ?? ???)
• connection liveness ?? ??? ??, ???? ???? ??
• ???? ?? address ?? ?? ????? ???? ???? ??? ??
• 
  ??? ? ??

46
Chapter 01 ??? ?? ??? LAN

• PPP Data Frame
• Info ??? ????? ???
• Check ????? ?? CRC

47
Chapter 01 ??? ?? ??? LAN

• PPP Data Control Protocol
• ?????? ????? ?? ??? ?? ? ?????? ?? ??
• configure PPP link (max. frame length,
  authentication)
• ???? ?? ??? ??/??
• for IP carry IP Control Protocol (IPCP) msgs
  (protocol field 8021) to configure/learn IP
  address

?? 1.19 PPP??? ????? ??
48
Chapter 01 ??? ?? ??? LAN

• ?? ?? ???? HDLC
• (High-level DataLink Control)
• ??
• ??? ???? ??
• ??? ?? ??
• ???? ??
• SDLC IBM
• ADCCP ANSI

49
Chapter 01 ??? ?? ??? LAN

• HDLC (High-Level Data Link Control)
• HDLC ??? ??

50
Chapter 01 ??? ?? ??? LAN

• ??? ?? ??
• ???? ????? ???? ???? ??? ???? ??? I-???? ??? ????
  ??? ??
• I-????? N(S)? N(R)??? ????? ????? ?? ??
• N(S) ???? ????? ??? ??
• N(R) I-???? ?? ?? ??? I-????? ? ???? ???? ??? ??
  ??? ?? N(R)??? ? ?? ??? ???? ??? ??
• ????? ??
• ????(3 or 7bit)
• Pipelining
• ????

51
Chapter 01 ??? ?? ??? LAN

• HDLC ????? ?? ??
• ?? ?? ??(NRM)
• ??? ?? ( ?? 1.20? (a),(b) )
• ??? ?? ??? ?? ???
• ??? ??? ?? ??? ??
• ??? ?? ??(ARM)
• ??? ??
• ????? ???? ??? ??? ??
• ??? ??? ?? ??? ??
• ??? ?? ??(ABM)
• ?? ??( ?? 1.20? (c) )
• ???? ??? ??? ??
• X.25 ?????? ??

52
Chapter 01 ??? ?? ??? LAN
?? 1.20 HDLC ???? ??
53
Chapter 01 ??? ?? ??? LAN

• HDLC ????? ?? ??

54
Chapter 01 ??? ?? ??? LAN

• HDLC ????
• ?? ?? ? ??

55
Chapter 01 ??? ?? ??? LAN

• ??? ?? 1.23

56
Chapter 01 ??? ?? ??? LAN

• ?? ???? ????? ???
• 1.8.1 ?? ???(Fast Ethernet)
• ?? ???? 10? ??.
• LAN ??? ?? ???? ???? ?? ???? ?? ???? ???
• ??? ????? ?? ?? ?? ? ? ??.
• Fast Ethernet? ??
• DATA-LINK-LAYER
• PHYSICAL LAYER MEDIA OPTION
• PHYSICAL LAYER SIGNALING SCHEMES
• Fast Ethernet? ??
• 100BASE-TX
• 100BASE-T4
• 100BASE-FX
• 100VG-AnyLAN

57
Chapter 01 ??? ?? ??? LAN

• 1.8.2 ???? ???(Gigabit Ethernet)
• Gigabit Ethernet? ??

58
Chapter 01 ??? ?? ??? LAN

• Gigabit Ethernet? ??
• 1000Base-SX
• 1000Base-LX
• 1000Base-CX
• 1000Base-T
• ??? ??
• ???? ??? ????? ???? ?? ?? IEEE 802.3 ???? ???
  ????.
• ?????? ?????? ????? ???? ? ??.
• Gigabit Ethernet? ??
• 1Gbps ???? ???, ??? ?? ?? ??
• ??? ???? ?? ??? ???? ??? ?? ??.
• ?? ??? ????? ??? ?? ????? ????? ??
• ?? ???, ??? ???? ?? ??? ??