Unit 7, Chapter 13 & 14 How do they talk to each other?
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Transcript of Unit 7, Chapter 13 & 14 How do they talk to each other?
Wide Area Networking &Wide Area Networking &InternetworkingInternetworking
Unit 7, Chapter 13 & 14How 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 topologiesUsually 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 functionsControl signals are sent as part of the protocolTone 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 NetworkDeveloped by Advanced Research Projects AgencyPackets sent through the network from source to destinationNo physical link is establishedPackets from other nodes is interspersed on the networkMessages are disassembled and reassembledDesigned 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 destinationConnection Oriented Routing - VCConnectionless Routing – Packet SwitchingCentralized 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 handledTransmission delay increases as well as retransmission of packetsManage by reducing flow of packets on the networkChoke Packet – sent to sources of traffic to tell them to slow the flow downQuality 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 routersQueuing Delay – Too much too fastQueuing Theory – Analysis of queues and queuing
Specific WAN SystemsX.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 SystemsAsynchronous Transfer Mode (ATM)
Developed to reduce delays that can occur on Frame RelayCell RelayEvolution of Frame Relay53 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 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
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)
Principles of Internetworking
TCP/IP packet switching networkVarious network technologies are employed – EthernetSubnetworks – Individual networks that are connected togetherEnd System – Device or computerIntermediate 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 Model TCP/IP
L7 Application
Application
L6 Presentation
L5 Session
L5 Session
TransportL4 Transport
L3 Network
InternetL2 Data Link
L2 Data linkData link (Network
interface)
L1 Physical (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 uniqueIPV4 – 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= 10.0.0.0,192.168.0.0,172.16.0.0
IP Classful Addressing
Address Classes:IP Address Rule I
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Address Classes:IP Address Rule II
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Address Classes:IP Address Rule III
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Subnets & Subnetting
Subnetwork or Subnet – separate part of an organizations network that is identifiableSecurity and traffic controlSubnet mask – 32 Bit number – ANDed with network portion of address(only 1+1=1)– 1’s = network and 0’s = host– Ex. Class A 255.0.0.0, network info is in the first octet
Default Subnet Masks– Class A = 255.0.0.0– Class B = 255.255.0.0– Class C = 255.255.255.0
Bits in the host octets are used to define subnet(pg 388)– Class C address 206.11.20.81– Subnet mask 255.255.255.224 or /27
• 11111111.11111111.11111111.11100000• 81 = 0101 0001
– Subnet Number 2– Host ID 17
Subnets & Subnetting
Classless Inter-Domain Routing:CIDR Address Prefix and Number of Class C
Addresses
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Addressing Particulars
/nn Classless Internet Domain Routing– 204.11.20.16/19 or Subnet mask
11111111.11111111.11100000.00000000
Supernetting – several class C addresses into a contiguous address blockDynamic IP address – address assigned when neededStatic – address is configured and does not change(routers…infrastructure equipment)Private networks – 10.0.0.0, 172.16.0.0,192.168.0.0
Subnetting Example
Step Example Rules
Address 8.1.4.5 None
Mask 255.255.0.0 None
Number of network bits 8 Always defined by Class A,B,C
Number of Host Bits 16Always defined by the number of binary 0s in the
mask
Number of Subnet Bits 8 32 - (Network size + host size)
Total 32 Network + Host + Subnet
Domain Names
Mnemonic for IP address (WWW.MSN.COM)Domain Name Services(DNS) used to translate or resolve name to addressHierarchical 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 systemsDeveloped by Defense Advanced Research Projects Agency (DARPA)Direct or point-to-point communicationsConnection oriented communicationFull Duplex – communication in both direction3 way hand shake to start communications & End Communications– Start:->SYN,<-SYN+ACK,->ACK – End: ->FIN+ACK,<-FIN+ACK,->ACK
TCP HEADER
TCP Header Information
TCP/IP Header:Stop-and-Go (left) versus Sliding Window Flow Control
(right)
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TCP/IP Header:Sliding Window Flow Control in
Operation
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User Datagram Protocol
Simple protocolConnectionlessNo error checkingNo sequencingNo HandshakingExamples: Ping, DNS, VOIP, TFTP
UDP Header:UDP Diagram Format
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UDP Header:IP Header Field Information
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Other Protocols
Address Resolution Protocol (ARP)Dynamic Host Configuration ProtocolFile Transfer Protocol/Trivial File Transfer ProtocolHypertext Transfer Protocol & Hypertext Transfer Protocol over Secure Sockets Layer or Transfer Layer SecurityPost 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. switchb. routerc. d-slamd. packet
Review Questions
2. Routers are specialized computers that perform routing in a network.a. Trueb. False
Review Questions
3. Delays in networks can come from _____________________.a. propagationb. switchingc. queuingd. all of the above
Review Questions
4. Which of the following is not an Internet top level domain name?a. .bizb. .govc. .comd. None of the above
Review Questions
5. A queue is a ____________.a. billiard stickb. waiting linec. serverd. router
Review Questions
6. Which of the following is not a cost of network design and implementation?a. The time of the network designersb. The cost of consultants to assist with the designc. The cost of staff to test the new networkd. 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 altercationb. a divisionc. pollingd. a collision
Review Questions
8. Which of the following routing techniques are used in WANs?a. dynamic routingb. distributed routingc. static routingd. 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.25b. Circuit switched systemsc. Frame relayd. RS-232e. X.21
Review Questions
10. VPNs ____________________a. Can send data through the Internetb. Can handle traffic relatively securelyc. Can restrict outside packets from entering the
VPNd. Are usually quite cost effectivee. All of the above
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 1-10 on pp. 446-447