best effect service(최선을 다해 서비스) Data Flow Characteristics Four types of characteristics are attributed to a flow: Reliability is a characteristic that a flow needs in order to deliver the packets safe and sound to the destination. Source-to-destination delay is another flow characteristic. Jitter is the variation in delay for packets belonging to the same flow. 오디오나 비디오를 전달할 때 굉장히 중요한 특성 Differe..

Application Layer Logical Connection at Application Layer reliable한 imaginary connection이 하나 만들어졌다고 볼 수 있음 실제로는 계층을 거쳐서 가지만... DNS(Domain Name System) Service 우리는 연락을 할 때 전화번호를 기억하기 보다는 상대방의 이름을 기억하여 연락을 취함 이와 유사하게 address(IP주소)에 접근하기 위해서 name을 부여하여 쉬운 접근을 가능케한다. www.naver.com 과 같이 외우기 쉬운 name으로 주소에 접근한다. DNS 서버가 IP주소를 알려준다.(114 같은 느낌 ㅋㅋ) Resolution Name-address resolution: a name to address/an ..

Internet Audio/Video Streaming stored audio/video refers to on-demand requests for compressed audio/video files youtube, netflix 저장, 압축된 영상매체를 불러오기 Streaming live audio/video refers to the broadcasting of radio and TV programs through the Internet 뉴스, live 방송 Interactive audio/video refers to the use of the Internet for interactive audio/video applications 카카오 보이스톡, 페이스톡, 줌 각 서비스 마다 요구사항이 달라서 나누..

Position of Transport-Layer Protocols UDP is an unreliable connectionless transport-layer protocol 그때그때 -> unreliable TCP is a reliable connection-oriented transport-layer protocol 보내기 전에 connection establishment -> connection teardown SCTP is a new protocol that combines the features of UDP and TCP end-to-end의 data delivery User Datagram Protocol (UDP) The User Datagram Protocol (UDP) is a conn..

Logical Connection at the Transport Layer Located between the application layer and the network layer. Provides a process-to-process communication between two application layers transport layer는 layer 1,2,3 와는 달리 통신망 상에 존재하는 것이 아니라 end system(host computer)에만 존재한다. Process-to-Process Communications Network layer versus. transport layer Network layer: host-to-host(집에서 집) computer level Transport ..

IPv6 Addressing The main reason for migration from IPv4 to IPv6 is the small size of the address space in IPv4 An IPv6 address is 128 bits or 16 bytes (octets) long, four times the address length in IPv4 232 -> 2128 IPv6: Address Space The address space of IPv6 contains 2128 addresses. This address space is 296 times the IPv4 address—definitely no address depletion—as shown, the size of the spac..

21.1 Introduction Unicasting One source and one destination network. One-to-one relationship Each router in the path of the datagram tries to forward the packet to one and only one of its interfaces. Unicasting (one-to-one), Multicasting(one-to-many), Broadcasting (one-to-all) Multicasting One source and a group of destinations. One to many relationship Source address is a unicast address, but t..

routing에서 forwarding table을 통해 forwarding이 어떤 방식(protocol)에 의해서 이루어지는가? An Internet as a Graph To find the best route, an internet can be modeled as a graph 경로의 edge의 cost를 모두 더했을 때 가장 적은 cost가 드는 길(path)을 찾는 과정 -> routing 방법 What is cost? distance 몇 차선 도로 요금 등등... 으로 생각 Least-Cost Trees 가장 cost가 적게 드는 tree 7개의 노드 * 각 노드에서 다른 모든 노드로 가는 경로 6개 N(N-1) 개의 path를 찾는다. Root node가 Routing Algorithms Sev..