Wide Area Networking & Internetworking

1. Wide Area Networking &Internetworking Unit 7, Chapter 13 & 14 How do they talk to each other?

2. Objectives • Summarize the characteristics and capabilities of a wide area network (WAN). • Identify distinguishing attributes of WANs as compared to LANs. • Identify the devices that are used in constructing WANs.

3. Wide Area Networks • General Design hybrid of a star, hierarchical and mesh topologies • Usually lease or use from communication carriers • Provide plain circuits • Additional services packet switching, frame relay, ATM, ISDN • Companies want Convience (and great service)

4. Network Signaling • Signaling required to manage the network and perform certain functions • Dial tone, on the hook, off the hook • Control signals are sent as part of the protocol • Tone Signaling • Generation of tone or combination of tones which tell the CO switch what number is being dialed • Signaling System 7 (SS7) • Used between switches • Carried over independent channels from the voice circuits • Common Channel Interoffice Signaling (CCIS) • Carry multiple voice channel signaling • Optimized for digital networks

5. Packet Data Networks • Packet Data Networks – Packet Switching Networks or Packet Network • Developed by Advanced Research Projects Agency • Packets sent through the network from source to destination • No physical link is established • Packets from other nodes is interspersed on the network • Messages are disassembled and reassembled • Designed with multiple high-speed paths

6. Packet Switching Techniques • 2 Methods to handle stream of packets • Datagrams • Connection-less circuit • Each packet handled independently by the network • No guarantee delivery • Virtual Circuits • Connection Oriented circuit • Route established through the network • Call request packet sent first, route determined • Virtual circuit number is assigned, call accept is returned • Virtual circuit number used for communication • When communication is complete, clear packet request is sent

7. Routing Traffic • Routing – How to create the virtual circuit or route the individual packets to its destination • Connection Oriented Routing - VC • Connectionless Routing – Packet Switching • Centralized Routing • Simple • Usually used in a stat hierarchy • Static routes

8. Routing Traffic • Distributed Routing • Responsibility for building and maintaining routing tables on some nodes in network • Avoids single point of failure • Static & Dynamic Routing • Static Routes are fixed • Dynamic Routes can change • Dynamic routing determines best path through network, difficult to implement • Broadcast Routing • Used by CSMA/CD protocol • Broadcast all packets to all stations at all times • Not efficient and not useable on large networks

9. Congestion Control • Congestion – traffic arrives faster than it can be handled • Transmission delay increases as well as retransmission of packets • Manage by reducing flow of packets on the network • Choke Packet – sent to sources of traffic to tell them to slow the flow down • Quality of Service (QOS) is a way to allow certain traffic to have priority over others

10. Delays & Queing • Propagation Delay • Time to get a signal from sender to receiver • LAN Delays usually about 1ms • WAN delay is longer due to distance and technology • Switching Delay – Delay moving data through switches and routers • Queuing Delay – Too much too fast • Queuing Theory – Analysis of queues and queuing

11. Specific WAN Systems • X.25 • Popular in Europe • Defines interface between computer and packet data network • 3 Standard Layers – • Packet – VC Service, up to 4095 VCs on one physical network • Link • Physical (X.21) • Frame Relay • More efficient than X.25, for high speed networks • ¼ the overhead of a packet switching technology • Not as good at congestion control • Control Plane – Establish and terminate connections • User Plane – Data Transfer • 2 Separate channels for planes • Committed Information Rate (CIR): guaranteed throughput speed, vendor may discard anything over CIR • Port Speed – Maximum speed that the circuit can communicate. 256KB Port speed / 64KB CIR

12. Specific WAN SystemsAsynchronous Transfer Mode (ATM) • Developed to reduce delays that can occur on Frame Relay • Cell Relay • Evolution of Frame Relay • 53 Byte Fixed Sized Cells (Thought to be the optimum size) • Real Time Service (Voice & Video) • Constant Bit Rate (CBR) – Fixed and continuously available bandwidth • Real-Time Variable Bit Rate (rt-VBR) – Bursty communications • Non-real Time Services • Non-Real Time Variable Bit Rate Services (nrt-VBR) • Fast Response Time Can Tolerate Some Delay • Available Bit Rate Service (ABR) • Define Maximum Rate to be used and Minimum required, provide at least minimum • Unspecified Bit Rate (UBR) • As available basis

13. Specific WAN SystemsAsynchronous Transfer Mode (ATM) • Synchrounous Optical Network (SONET) • Standard for sending data on fiber between carriers • Optical Carrier LevelData Rate • OC-1 51.84 Mbps • OC-3 155.52 Mbps • OC-12 622.08 Mbps • OC-24 1.244 Gbps • OC-48 2.488 Gbps • OC-192 10 Gbps • OC-256 13.271 Gbps • OC-768 40 Gbps

14. Specific WAN Systems • Integrated Services Digital Network (ISDN) • “B” Type Channel : Carry up to 64Kbps Data • “D” Type Channel : Carry up to 16Kbps Signaling Data • Basic Rate Interface = 2B + 1D Channel for 128Kbps • Primary Rate Interface = 23B + 1D (all b&d are 64Kbps) • Equal to the bandwidth of a T1 (24 channels) • Subdivide bandwidth as needed 10 Channels Voice, 13 Data • Broadband ISDN • Defined but not widely implemented • FDX Circuit 155.52 Mbps • FDX Circuit 622.08 Mbps • Asymmetrical Circuit with 2 simplex channels one at 155.52 Mbps and the other at 622.08Mbps • Switched Multimegabit Data Services(SMDS) • Virtual Private Networks (VPN)

15. Review Questions 1. A ___________ determines the best way to route to use when sending a message through a network and sends it on its way. a. switch b. router c. d-slam d. packet

16. Review Questions 2. Routers are specialized computers that perform routing in a network. a. True b. False

17. Review Questions 3. Delays in networks can come from _____________________. a. propagation b. switching c. queuing d. all of the above

18. Review Questions 4. Which of the following is not an Internet top level domain name? a. .biz b. .gov c. .com d. None of the above

19. Review Questions 5. A queue is a ____________. a. billiard stick b. waiting line c. server d. router

20. Review Questions 6. Which of the following is not a cost of network design and implementation? a. The time of the network designers b. The cost of consultants to assist with the design c. The cost of staff to test the new network d. The cost of the network operations personnel to run the network

21. Review Questions 7. When two stations on a circuit transmit at the same time, ______ occurs. a. an altercation b. a division c. polling d. a collision

22. Review Questions 8. Which of the following routing techniques are used in WANs? a. dynamic routing b. distributed routing c. static routing d. All of the above

23. Review Questions 9. Which of the following was developed to overcome the overhead of packet switching and provide more efficient data transmission? a. X.25 b. Circuit switched systems c. Frame relay d. RS-232 e. X.21

24. Review Questions 10. VPNs ____________________ a. Can send data through the Internet b. Can handle traffic relatively securely c. Can restrict outside packets from entering the VPN d. Are usually quite cost effective e. All of the above

25. Homework • Assignment: Due Next Week • Review: • Chapter 13, pp. 350-371 • Chapter 14, pp. 378-411 • Read: • Chapter 15, pp. 416-445 • Chapter 16, pp. 450-480 • Complete: • Multiple Choice Questions Chapter 13 1-10 on pp. 446-447 • Lab: Project!