Chapter 11Enterprise Networks & Internet

• Enterprise Network Architecture

• Internet

• Enterprise Network & Internet

Enterprise Network Architecture

• Overview

• Logical Design

• Physical Design

Overview

• Virtual corporation

• Virtual private network or enterprise network– Virtual LAN

• Technology– LAN switches– ATM switches– Backbone routers– SONET

Overview

• Application– Collaborative computing application software– Intelligent gent-based software

• Data: distributed database

Virtual LANs Logical Design• Use LAN switch with software• Types

– Layer 2 virtual LAN (switch)

– Layer 3 virtual LANs (routing switches)

• Pro– Lower cost of constantly changing and moving

workstations

• Limitations– Broadcasting and multicasting to its members

– Hard to manage (switching)

– No filtering for security

– No standard and interoperability

Virtual LANs Logical Design

• Transmission alternatives– Signaling message (broadcasting address)– Frame tagging (address tag)– Time division multiplexing (bandwidth)

• IEEE 802.10:encryption, authentication, segmentation, reassembly

• Bandwidth Hierarchy– Distributed backbones: bridge– Collapsed backbones: router with numerous

internetworking modules and enormous bandwidth capacity

Physical Design: ATM LAN emulation

• ATM address resolution– LAN emulation client (LEC) software

• ATM-to-LAN conversion devices

• convert Ethernet, token ring or FDDI into fixed length ATM cells

• Unicast (point-to-point) transmission

– LAN emulation server (LES) software• LES configuration services

• LES broadcast and unknown services (BUS)

• LES emulation services (address resolution protocol)

Physical Design: ATM LAN emulation

• Pros– support multiple network layer protocols

between virtual LANs

• Cons– Flat network topoloty– Broadcast storms– No filtering for security

Protocols over ATM Network

• Classical IP over ATM– Logical IP subnet or LIS: within subnet– Needs ATM address resolution protocol

(ATMARP)

• Multiprotocol over ATM (MPOA)– Edge devices– Route server

• IP switching– Long file use layer 2– Short message uses layer 3

Internet Survey

• 72% enhance company image

• 22% financially rewarding

• 40% financial rewards after 12-24 months

• Less 6% using credit card transaction

• 11 million Internet users

• 200 million television viewers

Business Objectives: Internet

• Customer service

• Marketing opportunity

• Competitive pressure

• Financially profitable

Internet Services/Resources

• World Wide Web

• Information servers– FTP servers– Gopher servers– WAIS servers– USENET servers

• Global e-mail

World Wide Web

• Web browsers

• Web site

• Graphical or multimedia

Information Servers

• Telnet: TCP/IP

• FTP servers: file transfer protocol

• Gopher– Search engines– Text

• WAIS (wide aarea information services)

• USENET servers: Network new transport protocol (NNTP)

Global E-Mail

• List server

• Electronic magazines (E-zines

Internet Pro & Con

• Pro– Access

– Bandwidth

– Front-end tools

– Server tools

– Information

• Con– Security

– Bandwidth

– search

– Ownership

– Regulation

Internet Connectivity

• Internet access providers (IAP) or Internet connectivity providers (ICP)

• Internet presence provider (IPP)

• Network access device– Modem– CSU/DSU– Router

WWW Connectivity Alternatives

• Web browser– Mosaic– Internet Explorer– Netscape

• Web terminology– Hypertext transport protocol (HTTP)– Hypertext markup language (HTML)– Uniform resource locator (URL)

Web Browser Selection Criteria

• Vertical integration: e-mail

• Ease of setup and use

• Performance

• Horizontal integration: network attached resources

Internet E-Mail Gateways

• Translator

• Simple mail transport protocol (SMTP)– No foreign character– Limited file size– No executable file

• Multiple Internet mail extension (MIME)

Internet Gateway vs. Internet-Enable Clients

• Internet gateway– Pros: single location, easy management– Cons: bottleneck

• Internet-enabled clients– Pro: not bottleneck– Cons: configuration, software, LAN protocol

Internet/Web Server Analysis

• Link to Internet

• IP address (IAP or InterNIC)

• Server hardware– CPU: 120MHz Pentium– Storage: RAID– Bus: PCI– Memory: 128 MB– Network interface card: 100-Mbps Ethernet– High-end UNIX workstation

Internet/Web Server Analysis

• Server software– Web page & input form (common gateway

interface CGI)– Gateway: file transfer– Security– Management: monitoring & reporting

Assignment

• Review chapters 9-11

• Read chapter 12