Chapter 3 Underlying Technology Http netwk hannam ac
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Chapter 3 기반 기술 (Underlying Technology) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 1
▣ 학습목표(OBJECTIVES): q 유선 LAN(Ethernet) 기술 소개: traditional, fast, gigabit, and ten-gigabit Ethernet. q 무선 LAN 기술 소개: IEEE 802. 11 LAN, Bluetooth. q point-to-point WAN 소개: 56 K modems, DSL, cable modem, T-lines, SONET. q 교환형(switched) WAN: X. 25, Frame Relay, ATM. q 연결 장치 소개: repeaters(hubs), bridges (two-layer switches), routers (three-layer switches). Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 2
3. 1 Wired Local Area Network Chapter Outline 3. 2 Wireless LANs 3. 3 Point-to-Point WANs 3. 4 Switched WANs 3. 5 Connecting Devices Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 3
Topics Discussed in the Section üIEEE Standards üFrame Format üAddressing üEthernet Evolution üStandard Ethernet üFast Ethernet üGigabit Ethernet üTen-Gigabit Ethernet Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 5
IEEE 표준 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 6
▣ 표준 이더넷 (계속) <프레임(Frame) 형식 ÜPreamble – alert, timing, start synchronization ÜSFD(Start frame delimiter) - 프레임시작 Ü목적지 주소(DA ; Destination address) Ü발신지 주소(SA ; Source address) ÜPDU 길이/유형 Ü데이터 ÜCRC – 오류 발견정보, CRC-32 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 9
Note Minimum length: 64 bytes (512 bits) Maximum length: 1518 bytes (12, 144 bits) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 11
Note The broadcast destination address is a special case of the multicast address in which all bits are 1 s. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 14
Note The least significant bit of the first byte defines the type of address. If the bit is 0, the address is unicast; otherwise, it is multicast. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 15
Example 3. 1 다음 목적지 주소의 유형을 나타내시오: a. 4 A: 30: 10: 21: 10: 1 A b. 47: 20: 1 B: 2 E: 08: EE c. FF: FF: FF: FF Solution 주소 유형을 알기 위해서, 왼쪽에서 두 번째 자리 값을 살펴보아야 한 다. 만약 짝수이면 유니캐스트이고. 홀수이면 멀티캐스트이다. 모든 자릿수 값이 F이면, 브로드캐스트이다. 따라서: a. This is a unicast address because A in binary is 1010 (even). b. This is a multicast address because 7 in binary is 0111 (odd). c. This is a broadcast address because all digits are F’s. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 16
Example 3. 2 주소 47: 20: 1 B: 2 E: 08: EE가 회선상에 보내지는 것을 보여라 solution 주소는 다음과 같이 바이트 단위로 left-to-right, byte by byte 로 보내지고; 각 바이트에 대해, right-to-left, bit by bit로 보내 진다: ← 11100010 00000100 11011000 01110100 00010000 0111 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 17
4세대를 거친 이더넷 발전 < 1976년 제록스사 Palo Alto 연구센터에서 처 음 만듬 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 18
3. 1 유선 근거리 통신망(LAN) <표준 이더넷(Ethernet) Ü 1973년 제록스사가 설계한 프로토콜 Ü데이터 전송률: 10 Mbps Ü접속형태 – 버스형 Ü접근 방법: CSMA/CD(Carrier Sense Multiple Access/Collision Detection) ÜIEEE 802. 3 표준 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 19
CSMA에서 충돌의 Space/time 모델 A Time Http: //netwk. hannam. ac. kr B C D Time HANNAM UNIVERSITY 20
CSMA/CD에서 첫번째 비트의 충돌 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 21
CSMA/CD 흐름도 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 23
표준 이더넷 구현 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 25
< 고속 이더넷 구현 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 28
고속 이더넷(Fast Ethernet) 구현 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 29
<기가비트 이더넷 구현 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 31
Note In the full-duplex mode of Gigabit Ethernet, there is no collision; the maximum length of the cable is determined by the signal attenuation in the cable. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 32
Gigabit 이더넷 구현 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 33
3 -2 무선 LAN < 무선 LAN : IEEE 802. 11 < 구조 Ü 기본 서비스 집합(BSS : Basic Service Set) w 무선 지국과 AP(Access Point)로 구성 w AP가 없는 BSS : 애드혹(Ad hoc) 구조 w AP가 있는 BSS : 기반구조 < 확장 서비스 집합 ESS(Extended Service Set) Ü AP를 가지고 있는 두개 이상의 BSS로 구성 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 35
Basic service set (BSS) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 36
Extended service set (ESS) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 37
▣ 지국 유형 <무전이 이동성(No-Transition Mobility) Ü고정이거나 한 BSS에서 이동 <BSS 전이 이동성(BSS-Transition Mobility) ÜESS내에서 BSS간 이동 가능 <ESS 전이 이동성(ESS-Transition Mobility) ÜESS간 이동 가능 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 38
▣ CSMA/CA 흐름도 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 39
▣ 프레임 교환 시간선(frame exchange time line) < DIFS(distribute interframe space) < SIFS(short interframe space) < RTS(request to send) < CTS(clear to send) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 40
CSMA/CA 와 NAV Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 41
프레임 형식 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 43
< 프레임 제어 필드 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 44
▣ 15. 1 IEEE 802. 11(계속) <프레임 종류 Ü관리 프레임(Management Frame) Ü제어 프레임(Control Frame) Subtype Meaning 1011 Request to send (RTS) 1100 Clear to send (CTS) 1101 Acknowledgment (ACK) Ü데이터 프레임(Data Frame) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 46
Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 47
< 주소 체계 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 48
숨겨진 지국 문제(hidden station problem) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 49
Note The CTS frame in CSMA/CA handshake can prevent collision from a hidden station. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 50
숨겨진 지국 문제를 예방하기 위한 핸드쉐이킹 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 51
노출된 지국 문제(Exposed station problem) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 52
노출된 지국 문제에서 핸드쉐이킹 사용 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 53
피코넷(Piconet) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 55
스케터넷(Scatternet) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 56
프레임 형식 유형(Frame format types) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 58
3 -3 POINT-TO-POINT WANS < 점-대-점- 광역통신망 ü 65 K Modems üDSL Technology üCable Modem üT Lines üSONET üPPP Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 60
56 K modem <업로딩: 33. 6 Kbps Http: //netwk. hannam. ac. kr <다운로딩: 56 Kbps HANNAM UNIVERSITY 61
3. 3 점-대-점 WAN <DSL(Digital Subscriber Line) 기술 ÜA(Asymmetric)DSL ÜRA(Rate adaptive) DSL ÜHDSL(High bit rate) DSL ÜS(Symmetric) DSL ÜV(Very high bit rate) DSL Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 62
Note ADSL is an asymmetric communication technology designed for residential users; it is not suitable for businesses. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 63
ADSL 대역폭 분할(Bandwidth division) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 64
ADSL 과 DSLAM < DSAM: Digital Subscriber Line Access Multiplexer Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 65
케이블 모뎀 구성(Cable modem configuration) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 68
<SONET ÜSynchronous Optical Network Ü광섬유 케이블 이용 고속 데이터 전송 규정 ÜSTS: Synchronous Transport Signal ÜOC: Optical Carrier Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 70
PPP < Point-to-Point Protocol Ü 물리층 : ANSI에서 공인된 모든 종류의 프로토콜 지원 Ü LCP(Link Control Protocol) Ü NCP(Network Control Protocol) Ü PPPo. E(PPP over Ethernet) Ü PPP 프레임 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 71
3. 4 교환 WAN <프레임 중계 ÜX. 25를 대체하기 위해 설계 Ü높은 데이터 전송률(1. 544 Mbps – 44. 736 Mbps) ÜBusty Data : 요구 대역폭(Bandwidth on Demand) Ü개선된 전송매체로 인한 적어진 오버헤드(less overhead due to Improved Transmission Media) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 74
Note A cell network uses the cell as the basic unit of data exchange. A cell is defined as a small, fixed-size block of information. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 76
ATM 다중화 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 77
ATM 네트워크 구조 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 78
가상회선(Virtual circuit) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 79
Note A virtual connection is defined by a pair of numbers: the VPI and the VCI. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 80
ATM 계층구조 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 81
계층의 이용 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 83
Note The IP protocol uses the AAL 5 sublayer. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 84
AAL 5 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 85
ATM 계층 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 86
ATM 셀(cell) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 87
3 -5 CONNECTING DEVICES <LAN 또는 WAN을 연결하기 위해 연결장치 사 용 <연결장치는 여러 계층에서 동작 Ü repeaters (또는 hubs) Ü bridges (또는 two-layer switches) Ü routers (또는 three-layer switches). Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 88
연결 장치(Connecting devices) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 89
리피터 (Repeater) 또는 허브(hub) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 90
Note A repeater forwards every bit; it has no filtering capability. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 91
Note A bridge has a table used in filtering decisions. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 92
Note A bridge does not change the physical (MAC) addresses in a frame. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 93
브리지(Bridge) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 94
학습 브리지(Learning bridge) M Http: //netwk. hannam. ac. kr M M M HANNAM UNIVERSITY 95
Note A router is a three-layer (physical, data link, and network) device. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 96
Note A repeater or a bridge connects segments of a LAN. A router connects independent LANs or WANs to create an internetwork (internet). Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 97
라우팅 예(Routing example) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 98
Note A router changes the physical addresses in a packet. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 99