哈尔滨工业大学：《网络应用开发》英文版 NAD-chapter1new-6

Functions of the Presentation Layer Functions of the Application Layer From application layer =m- Network virtual terminal -remote log- in other host in the internel File transfer, access, and management-store, retrieve or manage the o session layer ation layer is concerned with the syntax and semantics ss for global information and services e.g. HyperTextTransferProtocol(http) The presentation layer changes (encodes) the sender dependent format of the message into transform the original nformation into an encrypted form to assure privacy Compression-Data compression can reduce the number of bits to be transmitted, which is important for multimedia transmission. Summary for the functions of OSI-layers Chapter 1: Introduction Chapter goal: rk ba TCP/IP protocols stack review Client-server application dde nodes node odel and software design a Concurrent processing in TCP/IP Protocol Suite TCP/IP Protocol Architecture (1) Dominant co architecture Communication between processes or Specified and extensively used End to end or transport layer(TCP/UDP/.) before osi Developed by research funded US May include reliability mechanism(TCP) Department of d efense Hides detail of underlying network Used by the Internet Network Layer Routing of data

6 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 31 Functions of the Presentation Layer P-PDU Encoded, encrypted, and compressed data PH A- PDU Presentation layer To session layer From application layer P-PDU Decoded, decrypted, and decompressed data PH A- PDU Presentation layer From session layer To application layer The presentation layer is concerned with the syntax and semantics of the information exchange between two systems. • Translation - The presentation layer changes (encodes) the sender￾dependent format of the message into a common format that can be readable by any receiving system • Encryption - The presentation layer can transform the original information into an encrypted form to assure privacy. • Compression - Data compression can reduce the number of bits to be transmitted, which is important for multimedia transmission. 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 32 Functions of the Application Layer This layers enable the user (human or software) to access the network by user interfaces. Sometimes, No header or trailers are added at this layer. Typical services provided by this layer are: • Network virtual terminal - remote log-in other host in the internet • File transfer, access, and management - store, retrieve or manage the files from a remote computer. e.g. File Transfer Protocol (FTP) • Mail services - e.g. Simple Mail Transfer Protocol (SMTP) • Directory services - access for global information and services e.g. Hyper Text Transfer Protocol (HTTP) Application layer User A (U.S.) HTTP FTP SMTP L7 data Application layer User B (Africa) HTTP FTP SMTP L7 data 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 33 Application Presentation Session Transport Network Data link Physical Summary for the functions of OSI-layers allow access to network Translate, encrypt, and compress data Establish, manage, and terminate session Provide reliable end-to￾end message delivery and Move packets from error recovery source to destination; to provide internetworking Organize bits into frames; to provide node-to-node Transmit bits over a delivery medium; to provide mechanical and electrical specification 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 34 Chapter 1: Introduction Chapter goal: „ Network basics „ TCP/IP protocols stack review „ Client-server application model and software design „ Concurrent processing in client-server model 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 35 TCP/IP Protocol Suite „ Dominant commercial protocol architecture „ Specified and extensively used before OSI „ Developed by research funded US Department of Defense „ Used by the Internet 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 36 TCP/IP Protocol Architecture(1) „ Application Layer „ Communication between processes or applications „ End to end or transport layer (TCP/UDP/…) „ End to end transfer of data „ May include reliability mechanism (TCP) „ Hides detail of underlying network „ Network Layer „ Routing of data

TCP/IP Protocol Architecture (2) PDUs in TCP/IP Data link laye a data transfer between neighboring a Physical Layer Transmission medium Signal rate and encoding Some Protocols in TCP/IP Suite IPX/SPX Developed by xerox originally be IGNITe mm SMTr se ssMr applied in Novell Netware OS later Hosts that run Windows NT/XP/2000/9 3%5 can connect to icmPC Rsvr Novell Netware by IPX/SPX IPX/SPX is called NwLlink in ndows IPX/SPX can be routed like tCP/IP IPX/SPX VS OSI 工 PX Protocols Application IPX-Inter-networks Packet eXchange like IP SAP Presentation SPX- Serial Packet eXchange like TCI NetBios NCP-Netware core protocol Network Data link Protocol filters Such as Ethernet Physical Hierarchical design EIGRP and NLSP as routing protocols IPXSPX OSI Model

7 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 37 TCP/IP Protocol Architecture(2) „ Data link Layer ‰ data transfer between neighboring network elements ‰ Physical Layer „ Transmission medium „ Signal rate and encoding 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 38 PDUs in TCP/IP 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 39 Some Protocols in TCP/IP Suite 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 40 IPX/SPX „ Developed by Xerox originally,be applied in Novell Netware OS later „ Hosts that running Windows NT/XP/2000/98/95 can connect to Novell Netware by IPX/SPX „ IPX/SPX is called NWLlink in Windows NT „ IPX/SPX can be routed like TCP/IP 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 41 IPX/SPX vs OSI Physical Media+Protocols Data Link Such as Ethernet IPX Network SPX Transport NetBios Session Presentation NCP Application SAP RIP IPX/SPX OSI Model 哈工大计算机学院 李全龙 Network Application Development 1: Introduction IPX Protocols • IPX — Inter-networks Packet eXchange like IP • SPX — Serial Packet eXchange like TCP • RIP—routing updates • SAP—service advertisements • NCP — NetWare Core Protocol • NetBIOS emulation • Design options – Protocol filters – Hierarchical design – EIGRP and NLSP as routing protocols

Novell Servers Support Several Client Stacks Apple Talk Designed to connect Macintosh computers originally Now can be integrated to NetWare or Microsoft networks Be suitable to small net, not large Opon Data-Link Interface (OO) 喻大人计挥机学多堂龙 Apple Talk vs OSI Apple Talk Protocols AFP-Apple Talk interFace Protocol Presentation ASP-Apple Talk Session protocol ATP-Apple Talk Transaction protocol transport RTMP-routing updates zIP-zone information Data Link NBP-name-to-number translation DDP-Datagram Deliver Protocol Apple Talk Protocol Suite Windows Networking Based on NetBIOS applications Name Query-search for a server by name AppleTalk higher NWLink-NetBIOS over IPX IP stack ADSP NBT-NetBIOS over TCP/IP cal and data I 8

8 哈工大计算机学院 李全龙 Network Application Development 1: Introduction Novell Servers Support Several Client Stacks NetBIOS SPX IPX Open Data-Link Interface (ODI) 802.3 802.5 FDDI PPP IPX IP DDP NCP NFS AFP SAA Gateway 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 44 AppleTalk „ Designed to connect Macintosh computers originally „ Now can be integrated to NetWare or Microsoft networks „ Be suitable to small net,not large scale 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 45 AppleTalk vs OSI Application Presentation Session Transport Network Data Link Physical 哈工大计算机学院 李全龙 Network Application Development 1: Introduction AppleTalk Protocols • AppleShare —file sharing • AFP —AppleTalk interFace Protocol • ASP —AppleTalk Session protocol • ATP —AppleTalk Transaction protocol • RTMP—routing updates • ZIP—zone information • NBP—name-to-number translation • DDP —Datagram Deliver Protocol 哈工大计算机学院 李全龙 Network Application Development 1: Introduction AppleTalk Protocol Suite Physical and data link layers MacTCP supports IP stack AppleTalk network applications IP network applications AppleTalk higher layers RTMP DDP AARP ATP ADSP NBP Routing Chooser ZIP 哈工大计算机学院 李全龙 Network Application Development 1: Introduction Windows Networking • Based on NetBIOS – Session-layer protocol – Name Query—search for a server by name • Transport protocols – NetBEUI – NWLink—NetBIOS over IPX – NBT—NetBIOS over TCP/IP • Design options – Use NWLink or NBT – Protocol filters – Hierarchical designs

M s Windows NetBIOS Protocol Stack NetBIOs OSI Reference NetBIOs is a session-layer protocol used for File sharing Presenta Printer sharing Session Data Link Physical 喻大人计挥机学多堂龙 Windows Network Transport Mechanisms NetBEUI Protocol Stack NetBIOS can be transported by NetBEUI NetBIOS over TCP/IP-NBT g not Scssion Application Transpe traffic must be NetBEUI TCPMP interface card NetBIOS over IPX--NWLink NetBIOS over TCP/IP--NBT Technical requirements Recommended for small- to medium-size networks Recommended for medium-size to large-scale networks leeded for networks that include a wan link Carried as IPX type-20 packets Depends on an IP address assignment policy Data Lin Physic

9 哈工大计算机学院 李全龙 Network Application Development 1: Introduction M.S Windows NetBIOS Protocol Stack Application Transport Session Network Data Link Physical Presentation Redirector Server Message Block (SMB) NetBIOS Network interface card 1 7 6 2 3 4 5 NetBIOS OSI Reference 哈工大计算机学院 李全龙 Network Application Development 1: Introduction NetBIOS 7 • NetBIOS is a session—layer protocol used for • File sharing • Printer sharing • Messaging • Authentication • Name resolution Name Query - Broadcast Where is File_Server? Name Query - Broadcast Where is Print_Server? Print_ Server File_ Server 哈工大计算机学院 李全龙 Network Application Development 1: Introduction Windows Network Transport Mechanisms • NetBIOS can be transported by • NetBEUI • NetBIOS over IPX—NWLink • NetBIOS over TCP/IP—NBT NetBIOS NetBEUI IPX TCP/IP 哈工大计算机学院 李全龙 Network Application Development 1: Introduction NetBEUI Protocol Stack • Network-layer addressing not included • Application traffic must be bridged Application Transport Session Network Data Link Physical Presentation Redirector Server Message Block (SMB) NetBIOS Network interface card 1 7 6 2 3 4 5 NetBEUI OSI Reference NetBEUI 哈工大计算机学院 李全龙 Network Application Development 1: Introduction NetBIOS over IPX—NWLink • Technical requirements • Recommended for small- to medium-size networks • Needs IPX to be operational already • Carried as IPX type-20 packets Application Data Link NetBIOS Physical IPX 哈工大计算机学院 李全龙 Network Application Development 1: Introduction NetBIOS over TCP/IP—NBT • Technical requirements • Recommended for medium-size to large-scale networks • Needed for networks that include a WAN link • Depends on an IP address assignment policy Application Data Link NetBIOS Physical TCP IP

Internet Protocol(工P IP Addressing: introduction Part of tcp/Ip IP address: 32-bit Used by the Internet identifier for ho Specifies interface with higher layer router interface 孕12 e.g. TCP 223.1.13223 Only protocol at Layer 3 and physical lin Fundamental in suite a Defines host may have multiple 223.1.3.1 Internet addressing 地趣 Internet packet format Internet routing ce. not host IP Addressing IP Addressing Octet (8 bits). Octet (8 bits). Octet (8 bits) host part(low order bits) a what's a network 2 (from IP address device interfaces with 192 twork part of IP ddress can physically reach each intervening router est 24 bits are network address) IP Addressing 工 P Addresses How to find the given notion of"network", lets re-examine IP networks? 2231.1.3 Detach each interface from router host 22.2525 create " islands of isolated 2318 D1110 multicast address 223.1. 量2哑 10

10 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 55 Internet Protocol (IP) „ Part of TCP/IP „ Used by the Internet „ Specifies interface with higher layer „ e.g. TCP „ Only protocol at Layer 3 „ Fundamental in suite „ Defines „ Internet addressing „ Internet packet format „ Internet routing 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 56 IP Addressing: introduction „ IP address: 32-bit identifier for host, router interface „ interface: connection between host, router and physical link „ router’s typically have multiple interfaces „ host may have multiple interfaces „ IP addresses associated with interface, not host, router 223.1.1.1 223.1.1.2 223.1.1.3 223.1.1.4 223.1.2.9 223.1.2.2 223.1.2.1 223.1.3.1 223.1.3.2 223.1.3.27 223.1.1.1 = 11011111 00000001 00000001 00000001 223 1 1 1 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 57 IP Addressing 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 58 IP Addressing „ IP address: „ network part (high order bits) „ host part (low order bits) „ What’s a network ? (from IP address perspective) „ device interfaces with same network part of IP address „ can physically reach each other without intervening router 223.1.1.1 223.1.1.2 223.1.1.3 223.1.1.4 223.1.2.9 223.1.2.2 223.1.2.1 223.1.3.1 223.1.3.2 223.1.3.27 network consisting of 3 IP networks (for IP addresses starting with 223, first 24 bits are network address) LAN 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 59 IP Addressing How to find the networks? „ Detach each interface from router, host „ create “islands of isolated networks 223.1.1.1 223.1.1.3 223.1.1.4 223.1.2.1 223.1.2.2 223.1.2.6 223.1.3.1 223.1.3.2 223.1.3.27 223.1.1.2 223.1.7.0 223.1.7.1 223.1.8.1 223.1.8.0 223.1.9.1 223.1.9.2 Interconnected system consisting of six networks 哈工大计算机学院 李全龙 Network Application Development 1: Introduction 60 IP Addresses 0network host 10 network host 110 network host 1110 multicast address A B C D class 1.0.0.0 to 127.255.255.255 128.0.0.0 to 191.255.255.255 192.0.0.0 to 223.255.255.255 224.0.0.0 to 239.255.255.255 32 bits given notion of “network”, let’s re-examine IP addresses: “class-full” addressing: E 1111 240.0.0.0 to 255.255.255.255