Network Architecture Models

Bernard Chen

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 Client-Server Grid

Peer-to-Peer Model Communication Network References

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

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

“Blind Search” The unstructured P2P system usually use a

“blind search” method to find the requested data

“Blind Search” propagate a query to a number of peers randomly

Replication technique is often used to improve the performance of blind search

When data objects that are accessed more frequently are distribute more copies.

Some parameters N: number of peers

TTL: number of max hops for search a query

Random Walk Method The probability that

peer 2 and 3 receives messages from peer 1 is 50%

If every peer issues a query with TTL=1, the average messages received by peer 1,2,4 are 5/6, 5/6, and 4/3

Potential Energy Potential energy E: a peer’s capability of

receiving query message (Feng et al, 2007)

Then a peer’s potential energy is closely related to the potential energy of its neighbors and the probability that it can receive messages from neighbors

Therefore, it is defined as:

Potential Energy They assign the initial value as 1/n since each

peer has the same probability to generate query

If TTL=1

=>

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)

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

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

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