Chapter 11
Enterprise 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