Network Architecture Models

Niranjan Rao Julapelly

Outlines

•Introduction•System Architecture•Communication Network•References

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.

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.

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

Outlines

•Introduction•System Architecture Grid

Peer-to-Peer Model Client-Server•Communication Network•References

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]

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

P2P Categories• P2P were classified into three different

categories:1. Centralized P2P systems2. Decentralized structured P2P systems (there is no central server and peers are

structured according to some strict rules)3. Decentralized unstructured P2P systems

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

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

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.

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

HPC Technology: SCSI RDMA Protocol• Transfers data using SCSI (Small Computer

System Interface) using an RDMA communication service. [Intel, 2002]

Outlines

•Introduction•System Architecture•Communication Network Communication Network

Wired NetworkWireless Network

•References

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

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)

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.

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

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)

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.

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

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

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]

Outlines

•Introduction•System Architecture•Communication Network•References

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