1 / 41

COMP3122 Network Management

COMP3122 Network Management. Richard Henson April 2012. Week 9 – Connectivity and IP addressing Issues. Learning Objectives: Explain the meaning of class A, B, C, IPv4 addresses Apply principles of IPv4 addressing and subnet masks to the matter of optimising packet size in a LAN

eileen
Download Presentation

COMP3122 Network Management

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. COMP3122 Network Management Richard Henson April 2012

  2. Week 9 – Connectivity and IP addressing Issues • Learning Objectives: • Explain the meaning of class A, B, C, IPv4 addresses • Apply principles of IPv4 addressing and subnet masks to the matter of optimising packet size in a LAN • Explain the advantages of terminal emulation and other ways of doing the processing elsewhere…

  3. What is connectivity? • The sum total of how well hardware & software integrate to provide smooth passage of data between programs on different machines • includes mobile platforms • Now taken completely for granted; not always the case • HUGE thank you to OSI (open Systems Interconnect)

  4. Evolution of “connectivity” • Proprietary Systems  & “lock in” • poor connectivity not necessarily considered to be a problem by companies such as IBM and ICL… • “locked” customers into their products • not popular with customers • wanted to be able to buy freely • also a barrier to communication: • between companies • sometimes different parts of the same company! • using incompatible systems!

  5. Principles of Connectivity - 1 • For a client to connect to another computer… • the two devices need a common protocol covering all 7 OSI layers • For a network, client needs to be able to run the default protocol for that network • Example: • For a Windows Server machine to connect to a Netware server it needs to run IPX/SPX • can easily be added to the client machine’s protocol stack • connection to Netware servers then possible via hub/router and the Novell login

  6. Principles of Connectivity - 2 • Client machines on one network should also be able to connect to resources on another network: • follow principle 1 • install additional software on each client machine that will allow connection to resources using names from the other network’s resource database • Example: use a Netware printer from an XP client • set up NWLink • set up client service for Netware (CSNW)

  7. Principles of Connectivity - 3 • Client machines on one network should be able to connect to shared folders on servers on another network: • follow principle 1 • install software on the local server that will connect to the relevant remote server(s) • clients connect to the remote share via the local server

  8. Principles of Connectivity - 4 • Example: use a Netware shared directory from an XP client • install NWLInk on Windows XP clients and server • install Gateway Services for Netware (GSNW) on the relevant Windows 2003 Server • the Netware share becomes available as a Windows 2003 Server share • local clients can link to the share use the “map“ command

  9. Further (Deeper) aspects of IP addressing • An IP address is made up of four fields • Each field is represented by a single byte • Divided into two sections: • host address (first field/s) • network address (remaining field/s

  10. IPv4 Address Classes • IPv4 = 4 sets of numbers • Depending on the dividing position between “host” and “network”, IP addresses are categorised as different types (classes) w x y z

  11. IPv4 Address Classes • Several address classes: • Class A (w then x.y.z) • For networks with many hosts • High order bit in first field set to 0 • Class B (w.x then y.z) • For medium sized networks • High order bits in fields 1 and 2 set to 1-0 • Class C (w.x.y then z) • For small LANs • High order bits in fields 1,2,3,4 set to 1-1-0-1

  12. Subnet Masks • Purpose is to inform the hosts which bits in the full 32-bit IP address correspond to the network address and which bits correspond to the host address • Value depends on whether it is a class A, class B, or class C network: • Class C: 255.255.255.0 • Class B: 255.255.0.0 • Class A: 255.0.0.0

  13. Subnet Mask interaction with IPv4 addresses • A binary “mask” works by using logical AND with itself and a data value to set that value to zero (i.e. it is “masked”) • If one or more of the IPv4 numbers can be “masked”, it/they need not be included in packet headers (zero value assumed)

  14. Subnet Masks and Network Packet Optimisation • Value of subnet mark therefore relates directly to efficiency of management of network traffic • determines packet header size • should be a small as possible • Various formulae available for calculating subnet mask e.g. logical AND

  15. Logical AND in Practice • The result of the AND operation is 1 only when both bits being ANDed are 1 • otherwise, the result is 0 • IPv4 performs a logical AND comparison with the 32-bit IPv4 address and the 32-bit subnet mask • known as a bit-wise logical AND • result of is the subnet prefix

  16. Example (1) • To determine the subnet prefix of the IPv4 address configuration 131.107.189.41 with a subnet mask of 255.255.240.0… • turn both numbers into their binary equivalents, and line them up • perform the AND operation on each bit • write down the result

  17. Example (2) • IPv4 Address:     • 10000011 01101011 10111101 00101001 • Subnet Mask:   • 11111111 11111111 11110000 00000000 • Subnet Prefix:   • 10000011 01101011 10110000 00000000

  18. Subnet Masking a small (class C) network witthout doing the Maths… • Only a single subnet is involved: • e.g. 193.134.23.1 to 193.134.23.254 • (0 and 255 normally not used on last number) • up to 254 devices can be supported • Subnet mask will mask the first three numbers… • hence 255.255.255.0

  19. Subnetting a Class B network • Two IPv4 numbers involved after masking • e.g. 129.123.1.1 to 129.123.254.254 • Supports up to 255 x 254 devices (about 64K) • Optimium subnet mask depends on whether devices nearer to 254 or 64K • e.g. 5000 user network: 255.255.128.0 • 500 user network: 255.255.254.0

  20. Subnetting a Class A network • Three IPv4 numbers involved after masking • e.g. 75.0.0.0 to 75.255.255.254 • Supports network size up to 255 x 255 x 254 (about 16 million) • rarely used in practice as a single network • 255.128.0.0 would mask optimally a 10000 user network

  21. Reserved IP addresses • 127.0.0.1 to 127.255.255.255.255 • used for loopback testing • Private addresses for Internal networks: • Class A 10.0.0.0 to 10.255.255.255 • Class B 172.16.0.0 to 172.31.255.255 • Class C 192.168.0.0 to 192.168.255.255

  22. Terminal Emulation • All about making a PC or other device behave as if it was a dumb terminal (!) (thin client becomes 2D?) • achieved through software running on client that effectively bypasses the CPU for many processes and sends them to the server • Historically, terminal emulation has produced a text-based screen display • low usage of bandwidth • Windows-based terminal emulation products available for some time • but.. higher usage of bandwidth to support GUI

  23. Why Use Terminal Emulation? • Advantages: • lower TCO • makes use of old PCs (even old Pentium I, II) • saves money having to upgrade existing machines • screen response very fast • enhanced security (no use of local memory or h/d) • remote server access for administrators • remote client support • Disadvantages • extra CPU and memory demands on the server • still use some bandwidth • clients running applications locally would use zero bandwidth

  24. Terminal Emulation Options • Citrix Metaframe • very popular before Windows released Terminal Server • still an important player… • Windows Terminal Server • why bother with something else if the product is already supplied… and works?

  25. Windows Servers & Terminal Server (1) • Like Citrix, allows multiuser access to a Server at low bandwidth (e.g. using a standard telephone link) • Windows-based applications can run on the server and utilise just a user interface at the client end • low bandwidth because just keystrokes, mouse clicks and mouse movements are communicated • Standard interface: users may have different hardware, but the screen display will be the same, no matter what the platform

  26. Windows Servers & Terminal Server (2) • Terminal Server • Manages resources at the server end for each client session • Gives each user their unique desktop • Receives and processes all keystrokes and mouse actions • Directs all display output to the appropriate client • Terminal Client: • Just displays the desktop and GUI

  27. Windows Servers & Terminal Server (3) • A Terminal Services client “session” • opens on the client as a window within the existing local desktop • remote desktop runs within that window • only uses CPU power to connect with the server and display the user interface • strictly speaking a “thin” client, but uses very few local CPU cycles beyond those needed to run the operating system

  28. Windows Servers & Terminal Server (4) • Communications Protocol • RDP (Remote Desktop Protocol) • optimised to display graphical elements to the clients • application layer • runs on top of TCP/IP • like Microsoft NetMeeting, based on ITU T120 standard • http://www.imtc.org

  29. Low Hardware & OS Requirements of Terminal Services… • Windows 2000/XP: • 32Mb RAM, Pentium processor • Windows 98: • 16Mb RAM, 486 • Windows 95 (or even 3.1!!) • 16Mb RAM, 386 • Windows CE • depends on the vendor • If non-windows platform • use Citrix metaframe

  30. Client-end Terminal Services Software • Versions: • 16-bit for Windows-based computers running very old Windows for Workgroups with the 32-bit TCP/IP stack • 32-bit Windows-based computers • 64-bit with recent Windows (e.g. w2k3 r2)… • Client support for: • Windows CE Handheld PC • Windows-based terminals

  31. Applications and Terminal Services • 32-bit applications run more efficiently • using legacy 16-bit apps: • reduced number of users can be connected • increased memory overhead • 64-bit systems even more efficient..

  32. Terminal Services (Windows 2003 Enhancements) • More users supported per high-end server • Windows Management Instrumentation (WMI) provider enhances remote management capabilities • "Terminal Services Client“ -> Remote Desktop Connection • RDP 5.1 client features a much improved user interface • Remote desktop users can: • save connection settings • easily switch between windowed and full screen mode • dynamically alter their remote experience to match the available bandwidth

  33. Terminal Services & Windows 2003 - continued • Many local resources now available within the remote session, including: • client file system, smart cards, audio (output), serial ports, printers (including network), and the clipboard • Allows users to easily take advantage of the capabilities of their client device from within the remote session • e.g. files can be opened, saved and printed to the users local PC, regardless of whether the application is running locally or remotely • improved software restriction policies, roaming profile enhancements, and new application compatibility modes. • colour depth can be selected from 256 colors (8-bit) to True Color (24-bit), and resolution can be set from 640 x 480 up to 1600 x 120

  34. Terminal Servers • Preferably member servers, not domain controllers • need plenty of RAM (4-10 Mb required for each user) • recommended installed on an NTFS partition (multisession security for each users “live” data) & use fast, reliable hard disks (pref SCSI, SCSI-2 and RAID) • need a high performance network adapter card

  35. Unix Terminal Emulation • Microsoft favours FAT client • Unix favours Thin client or terminal emulation • Packages like UWIN: • runs via a PC • emulates terminal services • give features of a traditional Unix operating system on a Windows platform desktop

  36. Virtualisation (Windows 2008 Server, Citrix, VMware, etc.) • The use of software to allow a piece of hardware to run multiple operating system images at the same time • Possible to run Windows OS under Mac OS • run multiple versions of Windows OS on the same PC • Slightly different from terminal services but getting popular… • Enables the creation of a “virtual” (rather than actual) version of any software environment on the desktop, e.g. Operating Systems, a server, a storage device or networks, an application

  37. “The Cloud” • Outsourcing on a grand scale… • With connectivity via world wide web • “Back to the Future” • Quote from IBM in 1950s: • “I think there is a world market for about five computers.” attributed to J. Watson • “The cloud” will behave like just one massive mainframe computer providing all user services • no FAT clients needed… just enough processing at the client end to run a browser • could be a very small device • could use wireless protocols to connect…

  38. Web Services and The Cloud • Companies like Amazon, Google (apps), and salesforce.com have created web services (XML/http) and made them available to a wider public for storing their data • this approach benefits companies most that are experience relatively quick growth • instead of getting new storage resources every year, organisations can quickly and easily purchase more "cloud space"

  39. Cloud Services, the future, and Security • Cloud computing can offer applications as-a-service as well… • a future is predicted where everything is outsourced and no kind of local CPU is even needed • employees will simply have a monitor, keyboard, and mouse that will allow them to connect to the cloud for all of their resources (!) • but will this be secure? And what comeback will organisations have if something goes wrong?

  40. What (physically) is The Cloud • Lots of servers connected together in clusters to provide different services via the www • Attractive and powerful, but… • disadvantages of outsourcing in terms of control • and with the extra challenge that the user doesn’t know where there data physically is at a particular time… SCARY? • Server location also a matter of some concern for legal reasons…

  41. Thanks for listening

More Related