Unit 7, Chapter 13 & 14 How do they talk to each other?

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.

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

Network Signaling Signaling required to manage the network and perform certain functions 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

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

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

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

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

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

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

Specific WAN Systems X.25 –Popular in Europe –Defines interface between computer and packet data network –3 Standard Layers – Packet – VC Service, upto 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

Specific WAN Systems Asynchronous 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

Specific WAN Systems Asynchronous Transfer Mode (ATM) Synchrounous Optical Network (SONET) –Standard for sending data on fiber between carriers – Optical Carrier LevelData Rate – OC Mbps – OC Mbps – OC Mbps – OC Gbps – OC Gbps – OC Gbps – OC Gbps – OC Gbps

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 Mbps –FDX Circuit Mbps –Asymmetrical Circuit with 2 simplex channels one at Mbps and the other at Mbps Switched Multimegabit Data Services(SMDS) Virtual Private Networks (VPN)

Principles of Internetworking TCP/IP packet switching network Various network technologies are employed – Ethernet Subnetworks – Individual networks that are connected together End System – Device or computer Intermediate system – –Switches = Layer 2 or Layer 3 –Bridge = Layer 2 –Routers = Layer 3 Virtual Network – Subnets appear to be one large network

OSI – TCP/IP Models OSI ModelTCP/IP L7Application L6Presentation L5Session L5Session Transport L4Transport L3Network Internet L2Data Link L2Data link Data link (Network interface) L1Physical(Hardware)

TCP/IP Protocol Suite Layer 1 = Physical Layer –Hardware (NIC) Layer 2 = Network Interface –Split data into packets (frames) to be sent out –Sends frames and routes to devices on the network –Error detection and control for higher layers Layer 3 = Internet Layer –IP and IP address are used to transmit data –No corresponding OSI layer Layer 4 = Transport Layer –Ensures no errors and packets are in the correct order Layer 5 = Application Layer

Internet Protocol Addressing IP Address is unique IPV4 –32 Bit Address, 4 Octets (xxx.xxx.xxx.xxx) –Host portion-Host_id (nnn.hhh.hhh.hhh) –Network portion-Network-id (nnn.hhh.hhh.hhh) –5 Network classes Class A, starts with 0, range 0 – 126 Class B, starts with 10, range 128 – 191 Class C, starts with 110, range 192 – 223 Class D, starts with 1110, range 224 – 239 (multicast) Class E, starts with 1111, range 240 – 255 (reserved) Private address= , ,

IP Classful Addressing

Address Classes: IP Address Rule I Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

Address Classes: IP Address Rule II Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

Address Classes: IP Address Rule III Cisco Learning Institute Network+ Fundamentals and Certification Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

Subnets & Subnetting Subnetwork or Subnet – separate part of an organizations network that is identifiable Security and traffic control Subnet mask –32 Bit number –ANDed with network portion of address(only 1+1=1) –1 ’ s = network and 0 ’ s = host –Ex. Class A , network info is in the first octet

Default Subnet Masks –Class A = –Class B = –Class C = Bits in the host octets are used to define subnet(pg 388) –Class C address –Subnet mask or / = –Subnet Number 2 –Host ID 17 Subnets & Subnetting

Classless Inter-Domain Routing: CIDR Address Prefix and Number of Class C Addresses Cisco Learning Institute Network+ Fundamentals and Certification Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

Addressing Particulars /nn Classless Internet Domain Routing – /19 or Subnet mask Supernetting – several class C addresses into a contiguous address block Dynamic IP address – address assigned when needed Static – address is configured and does not change(routers … infrastructure equipment) Private networks – , ,

Subnetting Example StepExampleRules Address None Mask None Number of network bits8Always defined by Class A,B,C Number of Host Bits16 Always defined by the number of binary 0s in the mask Number of Subnet Bits832 - (Network size + host size) Total32Network + Host + Subnet

Domain Names Mnemonic for IP address ( Domain Name Services(DNS) used to translate or resolve name to address Hierarchical Structure –Local –Corporate –Global Top Level Domain (.com,.edu,.net,.org ….) Internet Corporation for Assigned Names and Numbers (ICAAN) Root Servers – Contain IP addresses of all TLD registries

Transmission Control Protocol Can communicate between hosts with diverse hardware and operating systems Developed by Defense Advanced Research Projects Agency (DARPA) Direct or point-to-point communications Connection oriented communication Full Duplex – communication in both direction 3 way hand shake to start communications & End Communications –Start:->SYN, ACK –End: ->FIN+ACK, ACK

TCP HEADER

TCP Header Information

TCP/IP Header: Stop-and-Go (left) versus Sliding Window Flow Control (right) Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

TCP/IP Header: Sliding Window Flow Control in Operation Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

User Datagram Protocol Simple protocol Connectionless No error checking No sequencing No Handshaking Examples: Ping, DNS, VOIP, TFTP

UDP Header: UDP Diagram Format Cisco Learning Institute Network+ Fundamentals and Certification Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

UDP Header: IP Header Field Information Cisco Learning Institute Network+ Fundamentals and Certification Copyright ©2005 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

Other Protocols Address Resolution Protocol (ARP) Dynamic Host Configuration Protocol File Transfer Protocol/Trivial File Transfer Protocol Hypertext Transfer Protocol & Hypertext Transfer Protocol over Secure Sockets Layer or Transfer Layer Security Post Office Protocol v3 (POP3) & Internet Message Access Protocol v4 (IMAP4) Simple Mail Transfer Protocol

Internet Tools Name Server Lookup (nslookup) –Determine IP address of a host system Whois –Determine name from an IP address Ping –Troubleshooting tool –Is the node there, is it alive, how much time …. Traceroute –Determine route packet takes to remote host

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

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

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

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

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

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

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

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

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

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

Homework Assignment: Due Next Week –Review: Chapter 13, pp Chapter 14, pp –Read: Chapter 15, pp Chapter 16, pp –Complete: Multiple Choice Questions 1-10 on pp