1. Chapter 11 Enterprise Networks & Internet Enterprise Network Architecture Internet Enterprise Network & Internet

2. Enterprise Network Architecture Overview Logical Design Physical Design

3. Overview Virtual corporation Virtual private network or enterprise network –Virtual LAN Technology –LAN switches –ATM switches –Backbone routers –SONET

4. Overview Application –Collaborative computing application software –Intelligent gent-based software Data: distributed database

5. 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

6. 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

7. 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)

8. Physical Design: ATM LAN emulation Pros –support multiple network layer protocols between virtual LANs Cons –Flat network topoloty –Broadcast storms –No filtering for security

9. 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

10. 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

11. Business Objectives: Internet Customer service Marketing opportunity Competitive pressure Financially profitable

12. Internet Services/Resources World Wide Web Information servers –FTP servers –Gopher servers –WAIS servers –USENET servers Global e-mail

13. World Wide Web Web browsers Web site Graphical or multimedia

14. 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)

15. Global E-Mail List server Electronic magazines (E-zines

16. Internet Pro & Con Pro –Access –Bandwidth –Front-end tools –Server tools –Information Con –Security –Bandwidth –search –Ownership –Regulation

17. Internet Connectivity Internet access providers (IAP) or Internet connectivity providers (ICP) Internet presence provider (IPP) Network access device –Modem –CSU/DSU –Router

18. WWW Connectivity Alternatives Web browser –Mosaic –Internet Explorer –Netscape Web terminology –Hypertext transport protocol (HTTP) –Hypertext markup language (HTML) –Uniform resource locator (URL)

19. Web Browser Selection Criteria Vertical integration: e-mail Ease of setup and use Performance Horizontal integration: network attached resources

20. Internet E-Mail Gateways Translator Simple mail transport protocol (SMTP) –No foreign character –Limited file size –No executable file Multiple Internet mail extension (MIME)

21. 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

22. 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

23. Internet/Web Server Analysis Server software –Web page & input form (common gateway interface CGI) –Gateway: file transfer –Security –Management: monitoring & reporting

24. Assignment Review chapters 9-11 Read chapter 12