Switching

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1 Switching

2 강의의목표 Switching/Switching Network의필요성을이해한다. 세가지대표적교환기술에열거하고그차이를설명할수있다. 각교환기술의장, 단점을비교하여설명할수있다. Packet Switching 에서 Fairness 문제와 Pipelining 을 패킷크기와연계하여설명할수있다. Soft Switch 개념을이해하고설명할수있다. 교재 Chapter 10. Circuit Switching and Packet Switching 2

3 Switch 의필요성? Switching Techniques 만약 Switch가없다면? 모든통신노드는상대노드와직접연결되어야함. 안정성개선? 세가지대표적인교환기술? Circuit Switching Datagram Packet Switching Virtual Circuit Packet Switching 3

4 Comparison of Communication Switching Techniques Circuit Switching 전용 (Dedicated) 전송 Path 연속적인 Data 전송 ( 교환을위한부가정보없음 ) Call Setup Delay Datagram Packet Switching 전용전송 path 없음, 패킷별경로결정 패킷 (Datagram) 의전송 ( 부가정보있음 ) No Call Setup Delay Store & Forward Delay Virtual Circuit Packet Switching 전용전송 path 가필수조건은아님, 고정전송 Route 패킷열 (Sequence) 의전송 ( 부가정보있음 ) Call Setup Delay Store & Forward Delay Fixed Bandwidth Dynamic Bandwidth 전체적으로보아서 Dynamic use of Bandwidth Call Blocking Packet Loss Call Blocking & Packet Loss CAC : Call Admission Control 4

5 Switching 기술비교시주요기준 Path / Connection / Call Setup 이필요한가? 데이터전송개시이전에연결설정이필요한가? 아무런설정작업없이데이터를바로보낼수있는가? 전송자원을고정적으로할당하는가? 아니면필요에따라동적으로할당하는가? 전송데이터의형태가연속적인정보의흐름인가? 아니면패킷 / 프레임등으로불리는분리된블록단위인가? 전송자원이부족하면어떤일이발생하는가? 5

6 Q1. 그림의이해 (1) (2) (3) (5) 차이의원인은? (4) 차이의원인은? 6

7 Network Delay (3) Circuit Switching Packet Switching Store and Forward Delay Queueing Delay Time Queueing Delay 7

8 DPS 와 VCPS 의 Route 결정방식의차이 8

9 Q2. Fairness 측면을중심으로다음을비교하라 Server (A) Variable (Possibly Large) Size Message Server (B) Limited (Generally Small) Size Packet 9

10 Q3. Pipelining 측면에서다음을비교하라 10

11 Space Division Switching Time Division Switching Blocking & Non Blocking Switch 이론 Switching Hardware 고속스위치개발에필요한기 반이론 11

12 (Control) Signaling In-Band Signaling vs Out-of-Band Signaling InChannel vs OutChannel Signaling이라고도함. 제어신호 (Control Signal) 전달경로와데이터전달경로의관계에따라구분 제어신호가데이터와같은경로를통해전달될경우 : In-Band 제어신호가데이터와다른경로를통해전달될경우 : Out-of_Band Common Channel Signaling SS7 : Signaling System 7; 이동통신망, 전화망, 지능망 ; 12

13 Soft Switch Architecture Soft Switch Architecture 숨은그림찾기 : 오른쪽그림에서위의 Traditional Circuit Switching 구조와아래의 Softswitch Architecture의차이는? Media Gateway, 실제 Physical Switching 담당 Media Gateway Controller Call Processing Logic 담당 Soft Switch 구조의현실적용 IP 기술에기초한통신망통합및진화를위한기반구조 전통적전화망 Circuit Switching 인터넷망 Packet Switching SIP (Session Initiation Protocol) IMS (IP Multimedia Subsystem) 참조. 13

14 GSM Network Architecture 14

15 UDP.vs. TCP ( 참고 ) Connectionless 연결설정없이바로전송가능 Socket Programming에서 TCP와차이 Unreliable 상대적으로간단함. 전송한 Datagram이유실될수있고순서가바뀌어도착할수있음. No Flow/Congestion Control Connection-Oriented 3-Way Handshaking에따른연결설정과정필요 Socket Programming이조금더복잡 Reliable Segment가유실될경우재전송을통해복구해주며순서가바뀌어도착하더라도순서번호를이용하여제대로맞추어전달해준다 Flow/Congestion Control 수신측의처리속도및망혼잡상황을 고려하여송신자가전송속도를조절하 는기능포함 15

16 UDP vs. TCP : Datagram vs. Stream ( 참고 ) Sending App. Receiving App. Sending App. Receiving App. Send Buffer Recv Buffer UDP Datagram TCP Connection Stream No Boundary 16

17 APP UDP vs. TCP : Datagram vs. Stream ( 참고 ) hijklmnop abcdefg APP UDP hijklmnop abcdefg abcdefg hijklmnop abcdefg UDP TCP hijklmnop abcdefg ijklmnop abcdefgh TCP ijklmnop abcdefgh 17

18 Routing? 3학년 2학기 Computer Network에서강의 Routing이란패킷을목적지로전달하기위해다음노드를결정하고해당노드로전달하는과정 Routing Table이라는자료구조를활용 Routing Table은기본적으로목적지와다음노드의 Tuple로구성 Forwarding vs. Routing ( 좁은의미의 ) Routing : Routing Table을만들고관리하는기능 Forwarding : Routing Table에따라패킷을처리하는기능 Routing 문제 Network as a Graph, Shortest Path Problem 2 Basic Routing Architecture Distance-Vector Link-State C 4 B 3 9 A 1 D 1 1 E 6 2 F 18

19 2 Basic Routing Architectures ( 참고 ) Distance-Vector Link-State Algorithm Distributed Bellman-Ford Dijkstra Routing Info. Distance-Vector Link-State Exchange with Neighbor Routers All Routers in the Network Standard Routing Protocol RIP (Routing Information Protocol) OSPF (Open Shortest Path First) Routing Information Exchanged between routers Through routing protocol Routing Execute Routing Algorithm using Routing Information to build Forwarding/Routing Table 19

TCP.IP.ppt

TCP.IP.ppt TCP/IP TCP/IP TCP/IP TCP/IP TCP/IP Internet Protocol _ IP Address Internet Protocol _ Subnet Mask Internet Protocol _ ARP(Address Resolution Protocol) Internet Protocol _ RARP(Reverse Address Resolution