Network Architecture Models

1. Network Architecture Models Niranjan Rao Julapelly

2. Outlines • Introduction • System Architecture • Communication Network • References

3. Distributed Computing • "Distributed" or "grid computing" in general is a special type of parallel computing which relies on complete computers (with onboard CPU, storage, power supply, network interface, etc.) connected to a network by a conventional network interface, such as Ethernet. This is in contrast to the traditional notion of a supercomputer, which has many CPUs connected by a local high-speed computer bus.

4. Distributed System Categories • Multiple computer systems collaborating to deliver a single application • Can be broadly applied to high-performance computing (HPC) whereby multiple computers, commonly called clusters, collaborate to solve a single problem • Multiple applications collaborating together as a system • Can be broadly applied to application integration whereby multiple discrete applications receive a copy of “some” data and process the data accordingly.

5. Distributed Service • Distributed Service depend on the system architecture and the underlying communication network. • In the upper level, system architecture is an abstract description of major components and their relation • In the lower level, network architecture specifies the communication facilities

6. Outlines • Introduction • System Architecture Grid Peer-to-Peer Model Client-Server • Communication Network • References

7. Architectures: Grid • Integrates and coordinates resources and users that live within different control domains • Built from multi-purpose protocols and interfaces that address such fundamental issues as authentication, authorization, resource discovery, and resource access. • Allows its constituent resources to be used in a coordinated fashion to deliver various qualities of service, (e.g. response time, throughput, availability, and security) [Foster, 2002]

8. Architectures: Peer-to-Peer Model • In this model, end users share resources in a peer style, potentially acting as both CLIENT and SERVER • Advantages: 1. removes single point failure and associated performance bottlenecks 2. releases the network traffic overhead by providing service locally

9. P2P Categories • P2P were classified into three different categories: 1. Centralized P2P systems 2. Decentralized structured P2P systems (there is no central server and peers are structured according to some strict rules) 3. Decentralized unstructured P2P systems

10. Architectures: Client-Server • Workstation-server model [Chow, 1997] • A work station may serve as a Stand-Alone computer or as a part of an overall network • Some workstations are Diskless Workstation, all file and boot services are supported by the network

11. Architectures: Client-Server • Processor-Pool model • Most workstations are idling at any instance in time. • Collects all processing power in Processor Pool Server • Users access a virtual single computer system with intelligent terminals

12. HPC Technology: Remote Direct Memory Access (RDMA) • Allows data to move directly from the memory of one computer into that of another without involving either one's operating system.

13. HPC Technology: Cisco® Infiniband • 20-Gbps bandwidth • Transport functions are all implemented in hardware that offloads all communications tasks such as reliable, in-order delivery and multiplexing, which allows more CPU cycles to be spent on processing rather than communications. [Cisco, 2006] • Has RDMA implementation

14. HPC Technology: SCSI RDMA Protocol • Transfers data using SCSI (Small Computer System Interface) using an RDMA communication service. [Intel, 2002]

15. Outlines • Introduction • System Architecture • Communication Network Communication Network Wired Network Wireless Network • References

16. Communication Network • The existence of multiple computer systems in a distributed system implies the need to interconnect these computers • System components may be connected by point-to-point or multipoint communication channels

17. Communication Network • Point-to-point links are direct connections between pairs of computer nodes • Multiple links allow the connection of nodes into a cluster and are usually implemented by using common buses or interconnection networks (switches)

18. Wired Interfaces: Ethernet • Family of local-area network (LAN) products covered by the IEEE 802.3 standard that defines CSMA/CD protocol • Carrier sense—Each station continuously listens for traffic on the medium to determine when gaps between frame transmissions occur. • Multiple access—Stations may begin transmitting any time they detect that the network is quiet (there is no traffic). • Collision Detect – Execute a random backoff before retransmission.

19. Wired Interfaces: Ethernet • Three data rates are currently defined for operation over optical-fiber and twisted-pair cables: • 10 Mbps—10Base-T Ethernet • 100 Mbps—Fast Ethernet • 1000 Mbps—Gigabit Ethernet

20. Wired Interfaces: Ethernet • Local area networks can be connected to form a Metropolitan Area Network (MAN) or a Wide Area Network (WAN) • Bus Based: IEEE 802 LAN • Ethernet: • Token Bus • Token Ring • Fiber Distributed Data Interface (FDDI) • Distributed Queue Dual Buses (DQDB)

21. 802.4: Token Bus802.5: Token Ring • Utilizes Token Passing: • Move a small frame, called a token, around the network. Possession of the token grants the right to transmit. • If a node receiving the token has no information to send, it passes the token to the next end station. • Each station can hold the token for a maximum period of time. • Data Rate: 4.16 Mbps • A token bus network is very similar to a token ring network, the main difference being that the endpoints of the bus do not meet to form a physical ring.

22. FDDI - Fiber Distributed Data Interface • FDDI uses dual-ring architecture with traffic on each ring flowing in opposite directions (called counter-rotating). • During normal operation, the primary ring is used for data transmission, and the secondary ring remains idle. • Optical Fiber (FDDI) or Copper Wire (CDDI) • Several FDDI Station-Attachment Types • 100 Mbps

23. Wireless: 802.11 • Specification are wireless standards that specify an "over-the-air" interface between a wireless client and a base station or access point, as well as among wireless clients. • Data Rates up to 54 Mbps • Can operate in Infrastructure (base station) or peer-to-peer mode (ad-hoc). • Commonly used in MANETs

24. Wireless: Zigbee • Based on 802.15.4 standard for low-complexity and low-power consumption wireless connectivity. • Provides Mesh routing capability (based on AODV) • Commonly used in wireless sensor networks and industrial automation. [Kwang, 2006]

25. Outlines • Introduction • System Architecture • Communication Network • References

26. References • Chow, Randy, et. al.,Distributed Operating Systems & Algorithms, Addison Wesley, March 18, 1997 • Ge, Z.; Figueiredo, D.R.; Sharad Jaiswal; Kurose, J.; Towsley, D.; Modeling peer-peer file sharing systems, INFOCOM 2003. Twenty-Second Annual Joint Conference of the IEEE Computer and Communications Societies. IEEE Volume 3, 30 March-3 April 2003 Page(s):2188 - 2198 vol.3 • Kwang Koog Lee; Seong Hoon Kim; Yong Soon Choi, A Mesh Routing Protocol using Cluster Label in the ZigBee Network; Mobile Adhoc and Sensor Sysetems (MASS), 2006 IEEE International Conference on Oct. 2006 Page(s):801 - 806 • Foster, Ian, What is a Grid? A Three Point Checklist, Argonne National Laboratory & University of Chicago, July 20, 2002 • Enterprise Distributed Systems and Infiniband, Cisco 2006 • SCSI RDMA Protocol (SRP), Intel 2002