1 Chapters 2 & 3 Computer Networking Review – The TCP/IP Protocol Architecture

2 Chapter 2 Protocols, Internetworking & the Internet

3 Introduction Networking standards Networking standards Layered protocol architecture Layered protocol architecture TCP/IP protocol suite TCP/IP protocol suite OSI reference model OSI reference model Internetworking Internetworking

Protocols, Internetworking & the Internet 4 Standards/Standards Bodies Why do we have standards? Why do we have standards? –market driver –cost driver –interoperability between vendors/ dissimilar architectures Disadvantages of standards? Disadvantages of standards? –tend to freeze technology –redundancy, overkill Types of standards Types of standards –Voluntary (driven by de facto use, ubiquity) –Regulatory –Regulatory use of voluntary standards

Protocols, Internetworking & the Internet 5 Standards/Standards Bodies The Internet Society The Internet Society –Internet Architecture Board (IAB) defines overall architecture of the Internet defines overall architecture of the Internet provides broad guidance for IETF provides broad guidance for IETF –Internet Engineering Steering Group (IESG) provides technical management of IETF and the Internet standards process provides technical management of IETF and the Internet standards process –Internet Engineering Task Force (IETF) IETF designs and develops Internet protocols designs and develops Internet protocols charters standards working groups charters standards working groups publishes RFCs, with approval of IESG publishes RFCs, with approval of IESGRFCs Eight areas defined: General, Applications, Internet, Operations & Management, Routing, Security, Transport, User Services Eight areas defined: General, Applications, Internet, Operations & Management, Routing, Security, Transport, User Services

Protocols, Internetworking & the Internet 6 Internet RFC Process Historic Experimental Best Current Practice Informational Internet Standard Draft Standard Proposed Standard Internet Draft

Protocols, Internetworking & the Internet 7 Standards/Standards Bodies International Telecommunications Union (ITU) International Telecommunications Union (ITU) –United Nations agency –Members are governments –ITU-T (replaced CCITT) drives telecommunications standardization process ITU-T organized as 14 study groups organized as 14 study groups 4-year cycle/study period for standards (but changing) 4-year cycle/study period for standards (but changing)

Protocols, Internetworking & the Internet 8 Standards/Standards Bodies Institute of Electrical and Electronics Engineers, Inc (IEEE) Institute of Electrical and Electronics Engineers, Inc (IEEE)IEEE –LAN Standards: IEEE 802 –Subsequently ISO 8802 –currently organized into seventeen working groups (e.g. IEEE 802.3) –IEEE defines overall architecture and practices for LANs/MANs

Protocols, Internetworking & the Internet 9 The Need for a Protocol Architecture Procedures to exchange data between devices can be complex Procedures to exchange data between devices can be complex High degree of cooperation required between communicating systems High degree of cooperation required between communicating systems –destination addressing, path –readiness to receive –file formats, structure of data –how commands are sent/received and acknowledged –etc.

Protocols, Internetworking & the Internet 10 Example: File transfer Requires a data path to exist Requires a data path to exist Tasks: Tasks: –Activate data communication path –Source determines that destination is ready –File transfer app destination file management app is ready store file for user –File format conversion

Protocols, Internetworking & the Internet 11 Layered Protocol Architecture Modules arranged in a vertical stack Modules arranged in a vertical stack Each layer in stack: Each layer in stack: –Performs related functions –Relies on lower layer for more primitive functions –Provides services to next higher layer –Communicates with corresponding peer layer of neighboring system using a protocol

Protocols, Internetworking & the Internet 12 Key Features of a Protocol Set of rules or conventions to exchange blocks of formatted data Set of rules or conventions to exchange blocks of formatted data Syntax: data format Syntax: data format Semantics: control information (coordination, error handling) Semantics: control information (coordination, error handling) Timing: order, speed matching, sequencing Timing: order, speed matching, sequencing Actions: what happens when an event occurs Actions: what happens when an event occurs

Protocols, Internetworking & the Internet 13 Internet Protocol Stack Layers (a.k.a. TCP/IP stack) Physical Physical Network Access Network Access Internet Internet Transport Transport Application Application Physical Link Network Transport Application or…

Protocols, Internetworking & the Internet 14 OSI – TCP/IP Protocol Stacks

Protocols, Internetworking & the Internet 15 TCP and UDP TCP: TCP: –connection-oriented, handshake required –reliable packet delivery in sequence UDP: UDP: –connectionless (datagram), no handshake –unreliable packet delivery –packets may arrive out of sequence or duplicated

Protocols, Internetworking & the Internet 16 TCP and UDP Headers TCP UDP

Protocols, Internetworking & the Internet 17 IP Headers – IPv4 IP Version 4 Header

Protocols, Internetworking & the Internet 18 IP Headers – IPv6 IP Version 6 Header

Protocols, Internetworking & the Internet 19 Operation of TCP and IP IP implemented in end systems and routers, relaying data between hosts IP implemented in end systems and routers, relaying data between hosts TCP implemented for end-to-end data transfer only in end systems*, assuring reliable delivery of blocks of data TCP implemented for end-to-end data transfer only in end systems*, assuring reliable delivery of blocks of data Each host on sub-network has a unique IP address Each host on sub-network has a unique IP address Each process on each host has a unique TCP port number Each process on each host has a unique TCP port number * Except when?

Protocols, Internetworking & the Internet 20 TCP/IP Protocol Data Units (PDUs)

Protocols, Internetworking & the Internet 21 TCP/IP Concepts – Data Flow application transport network link physical application transport network link physical application transport network link physical application transport network link physical network link physical data

Protocols, Internetworking & the Internet 22 TCP/IP Concepts

Protocols, Internetworking & the Internet 23 TCP Applications SMTP: Simple Mail Transfer Protocol SMTP: Simple Mail Transfer Protocol FTP: File Transfer Protocol FTP: File Transfer Protocol telnet: remote login telnet: remote login HTTP: web browsing HTTP: web browsing Inelastic or Elastic?

Protocols, Internetworking & the Internet 24 TCP Applications FTP client FTP server TCP control connection port 21 TCP data connection port 20 mail server user agent user agent user agent mail server user agent user agent mail server user agent SMTP SMTP SMTP PC running Explorer Serverrunning Apache Web Server Mac running Navigator http request http response Web browsing file transfer

Protocols, Internetworking & the Internet 25 Internetworking Terms Communication network Communication network Internet Internet Intranet Intranet Subnetwork Subnetwork End system End system Intermediate system Intermediate system Bridge Bridge Router Router

Protocols, Internetworking & the Internet 26 Routers Provide link between networks Provide link between networks Accommodate network differences: Accommodate network differences: –Addressing schemes –Maximum packet sizes –Hardware and software interfaces –Network reliability –Congestion/Traffic Management

Protocols, Internetworking & the Internet 27 TCP/IP Internetworking Example

Protocols, Internetworking & the Internet 28 Figure 2-8

Protocols, Internetworking & the Internet 29 Figure 2-9

Protocols, Internetworking & the Internet 30 Figure 2-10

Protocols, Internetworking & the Internet 31 OSI Reference Model Application Application Presentation Presentation Session Session Transport Transport Network Network Data link Data link Physical Physical

Protocols, Internetworking & the Internet 32 The OSI Protocol Stack