哈尔滨工业大学：《网络应用开发》英文版 NAD-chapter5

Chapter 5: Tunneling and Application Gateway Chapter goal: Multiprotocol environment Mixing network technologies Encapsulation and tunneling Clients and servers in constrained environments Application gateways Application gateway examples 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 1

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 1 Chapter 5: Tunneling and Application Gateway Chapter goal: „ Multiprotocol environment „ Mixing network technologies „ Encapsulation and tunneling „ Clients and servers in constrained environments „ Application gateways „ Application gateway examples

Chapter 5: Tunneling and Application Gateway Chapter goal: Multiprotocol environment Mixing network technologies Encapsulation and tunneling Clients and servers in constrained environments Application gateways Application gateway examples 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 2

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 2 Chapter 5: Tunneling and Application Gateway Chapter goal: „ Multiprotocol environment „ Mixing network technologies „ Encapsulation and tunneling „ Clients and servers in constrained environments „ Application gateways „ Application gateway examples

Multiprotocol environment Not all machines provide complete TCP/IP support Not all organizations use TCP /IP exclusively to interconnect computers Most large organizations have several groups of machines, with group using its own protocol suite, because Networking has evolved slowly Vendors promoted proprietary network systems TCP/IP not always available Minimize expense User habits 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 3

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 3 Multiprotocol environment „ Not all machines provide complete TCP/IP support „ Not all organizations use TCP/IP exclusively to interconnect computers. „ Most large organizations have several groups of machines, with group using its own protocol suite, because: „ Networking has evolved slowly „ Vendors promoted proprietary network systems „ TCP/IP not always available „ Minimize expense „ User habits

Multiprotocol environment Hosts using TCP/P Hosts using TCP/IP Ethernet Ethernet2 Wide area network Hosts using A7M囗 that uses 口 Hosts using A7M ATM Chief disadvantages: Duplication of effort Limitations of interoperability 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 4

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 4 Multiprotocol environment „ Chief disadvantages: „ Duplication of effort „ Limitations of interoperability … Hosts using TCP/IP Ethernet1 … Hosts using TCP/IP Ethernet2 Wide area network that uses ATM Hosts using ATM Hosts using ATM

Chapter 5: Tunneling and Application Gateway Chapter goal: Multiprotocol environment Mixing network technologies Encapsulation and tunneling Clients and servers in constrained environments Application gateways Application gateway examples 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 5

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 5 Chapter 5: Tunneling and Application Gateway Chapter goal: „ Multiprotocol environment „ Mixing network technologies „ Encapsulation and tunneling „ Clients and servers in constrained environments „ Application gateways „ Application gateway examples

Mixing network technologies TCP/IP internet consists of a set of host interconnected by Ip gateways(routers) Other internets use other protocols(e.g DECNET, SNA. t should be possible to substitute any transport-level switching service it n place o a single physical link in another packet switching system Many internets have been built that use switched technologies instead of physical networks For example: 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 6

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 6 Mixing network technologies „ TCP/IP internet consists of a set of host interconnected by IP gateways (routers). „ Other internets use other protocols (e.g. DECNET, SNA…) „ It should be possible to substitute any transport-level switching service in place of a single physical link in another packet switching system. „ Many internets have been built that use switched technologies instead of physical networks. „ For example:

Mixing network technologies Hosts using TCP/IP Hosts using TCP/IP Ethernet, Ethernet2 iP gateway Wide area IP gateway network Hosts using ATM囗 that uses Hosts using a7M ATM 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 7

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 7 Mixing network technologies … Hosts using TCP/IP Ethernet1 … Hosts using TCP/IP Ethernet2 Wide area network that uses ATM Hosts using ATM Hosts using ATM IP gateway IP gateway

Mixing network technologies Hosts using 7CP/IP Hosts using 7CP/P Ethernet Ethernet IP gateway Wide area IP gateway network that Hosts using ATM uses Hosts using ATM From the view of ip gateway ATM provides a link From the view of atm Software on two ip gateways acts like application software 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 8

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 8 Mixing network technologies „ From the view of IP gateway „ ATM provides a link „ From the view of ATM „ Software on two IP gateways acts like application software … Hosts using TCP/IP Ethernet1 … Hosts using TCP/IP Ethernet2 Wide area network that Hosts using ATM uses ATM Hosts using ATM IP gateway IP gateway

Mixing network technologies Hosts using 7CP/IP Hosts using 7CP/P Ethernet Ethernet IP gateway Wide area IP gateway network that Hosts using ATM uses Hosts using ATM Dynamic circuit allocation The static scheme needs N"(N-1)/2 circuit Each circuit requires both hardware and software resources The dynamic scheme allocate circuit on demand 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 9

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 9 Mixing network technologies „ Dynamic circuit allocation „ The static scheme needs N*(N-1)/2 circuit „ Each circuit requires both hardware and software resources „ The dynamic scheme allocate circuit on demand … Hosts using TCP/IP Ethernet1 … Hosts using TCP/IP Ethernet2 Wide area network that Hosts using ATM uses ATM Hosts using ATM IP gateway IP gateway

Chapter 5: Tunneling and Application Gateway Chapter goal: Multiprotocol environment Mixing network technologies Encapsulation and tunneling Clients and servers in constrained environments Application gateways Application gateway examples 哈工大计算机学院李全龙 Network Application Development Tunneling and Application Gateway 10

哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 10 Chapter 5: Tunneling and Application Gateway Chapter goal: „ Multiprotocol environment „ Mixing network technologies „ Encapsulation and tunneling „ Clients and servers in constrained environments „ Application gateways „ Application gateway examples