Networking With Remote Clients And Servers


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Networking With Remote Clients And Servers

  1. 1. Chapter 7 Networking with Remote Clients and Servers
  2. 2. Remote Node <ul><li>Today remote nodes connect via ISDN, DSL, cable modem, and Virtual Private Networking (VPN) across the Internet, in addition to dialing up using the plain old telephone system (POTS). </li></ul><ul><li>When connecting via remote node, a computer makes a connection through a public network to a remote access server (RAS). </li></ul>
  3. 3. Remote Node <ul><li>The remote access server then acts as a router, exchanging traffic between the remote computer and the network. </li></ul><ul><li>This enables the remote computer to act as though it is a network node, able to transfer files, access database information and applications, and print to network printers. </li></ul>
  4. 4. Remote Node
  5. 5. Remote Node <ul><li>Remote computing is typically slow! </li></ul><ul><li>When the remote node accesses applications from a network location, the application must first download to the remote node before it is processed. </li></ul><ul><li>Updates made to data must be uploaded across that slow link as well. </li></ul><ul><li>A server handles requests the same way regardless of whether the node is local or remote. </li></ul>
  6. 6. Remote Node <ul><li>Remote node computing is simply a point-to-point link. The remote node connects directly to a remote access server via an intervening network. </li></ul>
  7. 7. Remote Node
  8. 8. Remote Node <ul><li>Remote nodes differ from local nodes in only one way: Data travels through a modem to access the network in a remote node when it uses a dialup connection. </li></ul><ul><li>Data travels through a network interface card (NIC) to access the network in a local node. Therefore, a remote node simply treats its modem as though it were a NIC. </li></ul>
  9. 9. Point-to-Point Connections with PPP <ul><li>When you create a dialup connection to RAS, you must use a protocol to communicate. </li></ul><ul><li>The protocol most often used to create the point-to-point connection across the telephone network is the aptly named Point-to-Point Protocol (PPP). </li></ul><ul><li>It is based on an older protocol know as the Serial Line Internet Protocol (SLIP). </li></ul>
  10. 10. Point-to-Point Connections with PPP <ul><li>PPP offers several advanced capabilities. </li></ul><ul><li>When it is used to connect with a remote network, it encapsulates the upper-layer protocols. </li></ul><ul><ul><li>This process enables a remote node to appear to be connected locally. </li></ul></ul><ul><li>PPP’s link-control ability indicates when a connection is poor, providing for automatic termination and redialing. </li></ul>
  11. 11. Point-to-Point Connections with PPP <ul><li>PPP supports both Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP), which both prompt users to log on to establish a connection using encryption or clear text passwords. </li></ul>
  12. 12. Point-to-Point Connections with PPP
  13. 13. Using DSL for Remote Node <ul><li>ADSL </li></ul><ul><li>G.Lite (DSL lite) </li></ul><ul><li>HDSL </li></ul><ul><li>VDSL </li></ul>
  14. 14. Remote Access Service (RAS) <ul><li>When you dial into a network as a remote node, you log into a remote access server. </li></ul><ul><li>This is often the same server that provides remote node services across the Internet, via tunneling protocols. </li></ul><ul><li>A variety of remote access servers is available. </li></ul>
  15. 15. Remote Access Service (RAS)
  16. 16. Tunneling to a Virtual Private Network (VPN) <ul><li>VPN describes remote nodes that access a network via the Internet in a secure fashion. </li></ul><ul><li>That security is provided by tunneling protocols, along with encryption. </li></ul><ul><li>Many encryption schemes can encode data with strengths up to 128 bits, an encryption strength that virtually prevents decryption altogether. </li></ul>
  17. 17. Tunneling to a Virtual Private Network (VPN) <ul><li>VPN is available to clients who connect to the Internet through nearly any type of link. </li></ul><ul><li>Whether the client connects via ISDN, DSL, cable modem, or dialup line, a VPN session can usually be created. </li></ul><ul><li>VPN creates a virtual point-to-point connection to the RAS. </li></ul><ul><li>Tunneling is driven by the need to protect that virtual point-to-point link from being interrupted or eavesdropped upon. </li></ul><ul><li>Tunneling works by encapsulating data within IP packets in an encrypted format. </li></ul>
  18. 18. Tunneling to a Virtual Private Network (VPN)
  19. 19. Point-to-Point Tunneling Protocol (PPTP) <ul><li>Point-to-Point Tunneling Protocol (PPTP) takes its name from PPP because it uses PPP frames in its tunneling process. </li></ul><ul><li>PPTP encapsulates PPP frames within IP datagrams, which are then transmitted across the Internet. </li></ul>
  20. 20. Layer 2 Tunneling Protocol <ul><li>The Layer 2 Tunneling Protocol (L2TP) was developed to establish a viable alternative to PPTP as a standard. </li></ul><ul><li>Like PPTP, L2TP is an extension of PPP that supports multiple protocols. </li></ul><ul><li>Two servers provide an L2TP tunnel: the first is an L2TP access concentrator (LAC), which is simply a RAS. The second is an L2TP network server (LNS), which provides the L2TP service. </li></ul>
  21. 21. Remote Control <ul><li>Remote control was an early remote networking technology that enabled users to run applications on the network with fair performance. </li></ul><ul><li>The user would create a remote control session with a computer that was connected directly to the LAN. </li></ul><ul><li>On the remote computer, a window would appear with the remote computer’s desktop within it. </li></ul><ul><li>All application processing and data remained on the LAN; the only data that traveled to the LAN from the remote computer were keyboard and mouse clicks. </li></ul><ul><li>The graphical user interface contained the data traveling back to the remote computer. </li></ul>
  22. 22. Remote Control <ul><li>Remote control computing overcame some of the issues with remote node computing. </li></ul><ul><li>Because the application ran only on the LAN-connected computer, the remote computer didn’t need to be compatible with the network applications, nor did it require any additional hardware. </li></ul>
  23. 23. Remote Control
  24. 24. Independent Computing Architecture from Citrix <ul><li>Citrix developed its ICA protocol to facilitate remote control sessions. </li></ul><ul><li>The protocol runs within the upper layers of the OSI reference model, including the application, presentation, and session layers. </li></ul><ul><li>It establishes the session, maintains it, and terminates it. </li></ul>
  25. 25. Independent Computing Architecture from Citrix <ul><li>During the session, ICA carries keystrokes, mouse clicks, and graphical data in the form of compressed draw commands. </li></ul><ul><li>ICA is highly optimized in that it will update only the graphical data that has changed on the screen. </li></ul><ul><li>The protocol also allows file transfers between the local and remote computers. </li></ul>
  26. 26. Independent Computing Architecture from Citrix <ul><li>ICA requires very little bandwidth and can provide solid performance over a 20-Kbps connection. </li></ul><ul><li>This means that the average computer using a 56-Kbps modem connection will experience exceptional performance with an ICA session. </li></ul>
  27. 27. Microsoft Remote Desktop Protocol (RDP) <ul><li>Remote Desktop Protocol (RDP) offers much the same type of service as ICA. </li></ul><ul><li>It supplies the transport for keystrokes, mouse clicks, and display data for a server providing sessions to a thin client application. </li></ul>
  28. 28. Microsoft Remote Desktop Protocol (RDP) <ul><li>RDP is limited in the protocols it will run across; there’s no direct dial method. </li></ul><ul><li>RDP clients will operate only across a TCP/IP network. </li></ul><ul><li>If you need to run remote sessions across a network that is solely IPX/SPX or NetBEUI, you would be required to use Citrix MetaFrame. </li></ul>