CS457/557/MIS420/520 - Computer Networks: Chapter 11 - Enterprise Networking and the Internet

Objectives

Understand the business motivation for the analysis, design and implementation of enterprise networks
Understand the issues surrounding the analysis, design, implementation, and management of virtual LANs
Understand the differences between, as well as the advantages and disadvantages of, alternative physical topologies for enterprise networks.
Understand the importance of ATM to virtual LANs and enterprise networking.
Understand how Internet clients and servers are able to connect to the Internet.
Understand available hardware and software technology for building client/server connections to the Internet and the WWW.
Understand the implications of Internet use.

Major Paradigms of the Information Age

Age of the Mainframe
Introduction of the Minicomputer
Introduction of the PC
Dawn of the Client-Server Architecture and Applications Rightsizing

Primary benefits of Client-Server implementations

Improved productivity
Consolidated information systems
More access to information
Lower costs
New applications
New products and services
More control of data

Primary shortcomings of Client-Server implementations

Lack of software conversion tools
Inadequate vendor support programs
Lack of standards
Dependence on existing systems
Unproven technology

Introduction

Network design hurdles

A relative lack of affordable WAN bandwidth required to carry integrated voice, data, video, and multimedia applications.
The multivendor, multiplatform, multiprotocol reality of the numerous nodes of a typical enterprise network would need to be transparently integrated.
Enterprise networks need to be extremely flexible allowing individuals to cooperatively collaborate on projects regardless of geographic location.
Data required for decision-making needs to be easily and quickly accessed regardless of physical location or data management system.

The Role of Enterprise Networks: Delivering Distributed Processing and Databases

Enterprise Network - LAN + LAN-to-LAN (InterLAN) + WAN + network management hardware/software
virtual LANs - networks that can make geographically distributed users appear to be connected to the same LAN.

Overall Enterprise Network Architecture

enterprise network architectures and backbones

OSI Model Layer

Enterprise Network Element

Options

Application

Presentation

Session

Transport

Network

Architecture

Centralized(Hierarchical)
Distributed(Peer-to-Peer)
Hybrid

Data Link

Physical

Backbone

Distributed
Collapsed (uses a superhub)
Hybrid

client/server top-down model for enterprise network analysis and design
Business What business activity will this client/server link be engaged in?
What is the financial justification or priority of the business activity?
How important is the client/server link?
Can the costs of this link be justified?

Application Client Middleware Server Management

Client tools?
E-mail processing requirements? E-mail gateways? Distributed processing server? E-mail server? How will this particular client/server interaction be monitored / managed?

Data Database front-end? Database connectivity software?
SQL? etc. Database server / engine? How will the this particular client/server interaction be monitored / managed?

Network Client NOS? APIs? Named pipes? NETBIOS? Transport protocol? etc. Server NOS? How will the this particular client/server interaction be monitored / managed?

Technology Client OS?
Media? Compatibility issues? Gateway solutions? Media interface converters? Server OS?
Media? How will the this particular client/server interaction be monitored / managed?

client/server top-down model for enterprise network analysis and design
Business	What business activity will this client/server link be engaged in? What is the financial justification or priority of the business activity? How important is the client/server link? Can the costs of this link be justified?
Application	Client	Middleware	Server	Management
	Client tools? E-mail processing requirements?	E-mail gateways?	Distributed processing server? E-mail server?	How will this particular client/server interaction be monitored / managed?
Data	Database front-end?	Database connectivity software? SQL? etc.	Database server / engine?	How will the this particular client/server interaction be monitored / managed?
Network	Client NOS?	APIs? Named pipes? NETBIOS? Transport protocol? etc.	Server NOS?	How will the this particular client/server interaction be monitored / managed?
Technology	Client OS? Media?	Compatibility issues? Gateway solutions? Media interface converters?	Server OS? Media?	How will the this particular client/server interaction be monitored / managed?

Enterprise Network Logical Design

Virtual LANs

Basic Functionality - requires a LAN switch that supports broadcast and multicast messages across the "virtual LAN"
Limitations - no standard for sharing virtual LAN info between multiple LAN switches; difficult to manage and monitor [Fig. 11-3]
Transmission between Virtual LANs - requires routing
Classification of Virtual LANs (Layer 2 / Layer 3 virtual LANs) [Fig. 11-4]

Bandwidth Hierarchy

[Fig. 11-7]

Distributed backbones
Collapsed backbones

Enterprise Network Physical Design

ATM as a Common Switching Platform

ATM LAN Emulation [able to construct virtual LANs regardless of the geographic scope of the network (by translating MAC addresses into ATM addresses)]
Layer 3 Protocols over ATM Networks
- Classical IP over ATM - IETF RFC 1577 [IP router sees entire ATM network as only a single hop; still requires address resolution (ATMARP)]
- MPOA (Multiprotocol over ATM) - standard being developed by ATM Forum [Fig. 11-9]
- Multiprotocol Encapsulation over ATM Adaption Layer 3 - IETF RFC 1483
- IP Switching - long data streams are sent using a virtual circuit via ATM (layer 2) while datagram-oriented short messages are forwarded using layer 3 routing

The Internet as an Enterprise Network Backbone

What does the Internet have to offer businesses?
What are the various ways in which businesses can access Internet services?
How can a business integrate the Internet with its local area networks in a client/server architecture?
How can a business safely and securely use the Internet as an enterprise network backbone?

Business Perspective on the Internet

Why Connect to the Internet?
- 72% of companies want to use the Internet to enhance their company's image.
- 22% said their Internet usage was financially rewarding.
- 40% didn't expect financial rewards for 12-24 months.
- less than 6% of companies conduct credit card transactions over the Internet.
What are the Available Services/Resources?
- e-mail / listservs
- WWW
- ftp
- gopher
- WAIS
- USENET
- Telnet
What are the Potential Advantages?
What are the Potential Disadvantages?

A CLIENT/SERVER APPROACH TO INTERNET CONNECTIVITY

Overall Client/Server Architecture for Internet Connectivity (ISPs)
- Internet access providers (IAP) - provide Internet access for subscriber companies
- Internet presence providers (IPP) - design, develop, implement, manage, and maintain a subscriber company's presence on the Internet.
Service Specific Client/Server Architectures for Internet Connectivity [Fig. 11-13]
EDI(electronic data interchange) & EFT (electronic fund transfer) are migrating to the web to become electronic commerce

CLIENT/SERVER TECHNOLOGY FOR INTERNET CONNECTIVITY

HTTP (hypertext transfer protocol)
HTML(hypertext markup language)
URL (uniform resource locator)

Internet/Web Clients
Internet/Web Gateways (proprietary e-mail -- SMTP); IPX/IP gateway
Internet/Web Servers (hardware / software)
Internet Transport Protocols
- TCP/IP Suite of Protocols: TCP,IP,SLIP, PPP, PPTP
- tunneling protocols: PPTP(point-to-point tunneling protocol); L2F (Cisco's layer two forwarding)
Internet Connectivity Services
Beyond Internet Connectivity (video conferencing; simultaneous document sharing; EDI; global fax service; electronic document distribution; paging; news & info services

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