Lecture 3 Design Philosophy Applications Dejian Ye Software school Fudan University Computer Networks
1 Lecture 3 Design Philosophy & Applications Dejian Ye Software School Fudan University Computer Networks
Lecture overview Last time: Protocol stacks and layering oSi and tc∥ P mode|s >)Application requirements from transport protocols Internet Architecture Application examples ftp http Application requirements “ ilities” 》 Sharing 2
2 Lecture Overview Last time: » Protocol stacks and layering » OSI and TCP/IP models » Application requirements from transport protocols Internet Architecture Application examples. » ftp » http Application requirements. » “ilities” » Sharing
Internet Architecture Background 》“ The Design Philosophy of the DARPA Internet Protocols(David clark 1988) Fundamental goal: Effective network interconnection Goals, in order of priority: 1. Continue despite loss of networks or gateways 2. Support multiple types of communication service 3. Accommo date a variety of networks 4. Permit distributed management of Internet resources 5. Cost effective 6. Host attachment should be easy 7. Resource accountability 3
3 Internet Architecture Background » “The Design Philosophy of the DARPA Internet Protocols” (David Clark, 1988). Fundamental goal: Effective network interconnection Goals, in order of priority: 1. Continue despite loss of networks or gateways 2. Support multiple types of communication service 3. Accommodate a variety of networks 4. Permit distributed management of Internet resources 5. Cost effective 6. Host attachment should be easy 7. Resource accountability
Priorities The effects of the order of items in that list are still felt today >)E.g, resource accounting is a hard, current research topic Let's look at them in detail
4 Priorities The effects of the order of items in that list are still felt today » E.g., resource accounting is a hard, current research topic Let’s look at them in detail
Survivability If network disrupted and reconfigured > Communicating entities should not care ))No higher-level state reconfiguration > Ergo, transport interface only knows"working "and"not working. ' Not working== complete partition How to achieve such reliability? Where can communication state be stored Network Host Failure handing Replication Fate sharing Net Engineering Tough Simple Switches Maintain state Stateless Host trust Less More 5
5 Survivability If network disrupted and reconfigured » Communicating entities should not care! » No higher-level state reconfiguration » Ergo, transport interface only knows “working” and “not working.” Not working == complete partition. How to achieve such reliability? » Where can communication state be stored? Network Host Failure handing Replication “Fate sharing” Net Engineering Tough Simple Switches Maintain state Stateless Host trust Less More