AIT
Questions about the lecture 'Advanced Internet Technology' of the RWTH Aachen
Questions about the lecture 'Advanced Internet Technology' of the RWTH Aachen
Kartei Details
| Karten | 236 |
|---|---|
| Sprache | English |
| Kategorie | Informatik |
| Stufe | Universität |
| Erstellt / Aktualisiert | 05.02.2017 / 10.10.2017 |
| Weblink |
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What paradigms exist?
The P2P and Client/Server paradigms
What are the characteristics of the Research Network APRANET? [4]
1. Based on P2P paradigm
2. “Connection of independent nodes, which can operate in case of connection/node failures.”
3. Immediate mutual login (telnet) and file sharing (FTP)
4. “project study fault-tolerant packet network”
What happened 1962?
Department of Defense (DoD) with “National defense depends on communication”
What happened 1967?
DoD at Stanford Research Institute with Advanced Research Project Agency (ARPA)
What happened 1969?
The first Internet with four hosts
What happened 1971? [2]
1. Initiation of APRANET (first Internet backbone)
2. Development of eMail // Human human interaction
What happened 1974?
Development of new protocol family TCP/IP
What are the characteristics of the Public and Commercial Network? [2]
1. Silent move to Client/Server paradigm
2. Continuous increase of bandwidth and users
What are examples for servers? [11]
1. DNS
2. eMail
3. Web
4. FTP
5. Gaming
6. Database
7. DHCP
8. News
9. File
10. Time
11. Backup
What happened 1991?
Development of World Wide Web (www) // Human machine interaction
What are the characteristics of the Global Information Network? [3]
1. Continuous increase of users, bandwidth and computing power after “.com”-crash
2. From Client/Server back to P2P
3. Increase of hosts from >2mio (1982) to <1mia (2015)
What are the characteristics of the Future Network? [2]
1. Prediction is that all segments consume twice as much Petabytes/month in five years
2. New technologies have to be adapted
What are examples for new technologies? [6]
1. Ubiquitous Computing
2. Sensor-based Networks
3. Internet of things (IoT) // Context-awareness necessary
4. P2P systems
5. Cloud computing // Computing resources on demand
6. Software defined networking // Highly configurable networks
What are examples for Future Networks? [5]
1. Home Automation
2. Smart Cities
3. Industrial Automation
4. Car Networks
5. Body Networks
What are the challenges for Future Networks? [7]
1. Scalability, 2. reliability, 3. adaptability, 4. performance, 5. mobility, 6. security and 7. privacy
What are the disadvantages of the Client/Server paradigm? [6]
1. traffic load is concentrated on server which is a asymmetrical traffic flow
2. memory and cpu not sufficient for number of users
3. a server is a single point of failure // no fault tolerance
4. only optimized for wired, powerful hosts
5. Missing extensibility of the network for new specialized services
6. Internet Service Provider (ISP) prohibit changes
What are the advantages of the P2P paradigm?
1. File sharing, distributed computing
2. Optimized for devices with restricted resources
What causes failures of DNS or HLR servers?
Hardware/software problems, overload (9.11) and attacks
Who relies on availability?
Internet-based services and businesses
What is the disadvantage of new paradigms?
The old protocols (e.g. TCP can not deal with disruptive connections)
Which developments failed due to missing extensibility?
1. Group communication, IP multicast
2. Quality of services
3. Support for mobility
4. Active networking
What are the motivations for P2P? [4]
1. Classical Internet reaches limits
2. Decentralized self-organizing systems and -usage of resources goes beyond these limits
3. P2P approach for new services (chat, file-sharing) // publicity for copyright discussion
4. Location- evolves to content based routing
What is the definition of P2P?
“P2P is a class of applications which works at the edge of the Internet using decentralized resources (storage, cycles, content, human presence). Therefor it operates with unstable connectivity, unpredictable IP addresses, outside the DNS system and has autonomy from central servers.”
What are the characteristics of P2P? [4]
1. Unreliable/-available infrastructure
2. Partitioning of responsibilities // No central service control therefor
3. Avoiding bottleneck with redundancy and replication // maybe to big growth
4. Overlay network
What are the characteristics of the missing central service control? [5]
1. fault tolerance
2. more resources // decentralized resource usage and decentralized information management
3. autonomy of participants
4. NAT, dynamic IP addresses, firewalls and mobility cause problems
5. distributed algorithms
Which distributed algorithms exist? [4]
1. routing
2. reliability
3. search, identification and status control of neighbors
4. service discovery
What are the characteristics of the overlay network? [3]
1. Over existing infrastructure
2. Custom routing
3. Content oriented
What are the challenges of P2P? [4]
1. Location of data in distributed systems // where to store/find?
2. Scalability of communication and storage
3. Robustness, resilience
4. Consistency, up-to-dateness after data modification
What are the characteristics of communication and storage? [2]
1. Complexity in O(log n)
2. Important parameter
What are P2P examples? [3]
1. Society, economy, Facebook and Twitter on user layer
2. File exchange like Napster, Gnutella , BitTorrent and distributed file systems or databases
3. Internet, Arpanet and mobile ad-hoc networks
What unstructured P2P approaches exist?
Centralized and pure approach
What is the idea behind centralized P2P?
The directory is handled by a coordinating entity CE
What is the idea behind pure P2P?
Only peers exist
What is an example for centralized P2P?
Centralized directory model (CDM) on P2P layer (1st generation Napster)
What are the characteristics of CDM? [2]
1. Directory service by CE
2. Peers communicating with CE and other peers
What are the characteristics of the CE of CDM? [3]
1. bootstrap server and single point of failure // distribution possible
2. index/group database
3. lookup/routing table
What are the characteristics of Peer-to-CE of CDM? [5]
1. Defined by Napster protocol
2. Search request → CE → list of peers
3. Register, log on overlay
4. Find content
5. Update routing tables, shared content information
What are the characteristics of Peer-to-Peer of CDM? [1]
Download request → peer → file
What are the advantages of CDM? [3]
1. Fast and complete
2. Central managing trust authority
3. No keep alive necessary, beyond content updates
What are the disadvantages of CDM? [3]
1. Single point of failure
2. Bottleneck
3. Central server in control of all peers
