Wan asignment
- 1. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 1 ASSIGNMENT OF WAN TECHNOLOGIES NAME: __________________SHAZIA JAMALI___________________ ROLL NO__________________16 BS(IT) 05_______________________ SUBJECT____________________WAN TECHNOLOGIES___________ SUBMIT TO__________CHAIRMAN IBRAHIM CHANNA_________
- 2. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 2 Q.No-1 How does a WAN differs from LAN over the basis of definition, area covers, speed, technology, types of connections, components, cost, bandwidth, security ,and ownership?
- 3. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 3
- 4. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 4 Q.No-2 Describe the fundamental concepts of point-to-point serial communication. Compare and contrast between modem, CSU/DSU, access server, WAN switch, and router? . Basic concepts of point to point serial communication: One of the most common types of WAN connections is the point to point connection. Point to point connections are used to connect LANs to service provider WANs, and to connect LAN segments with an enterprise network. A LAN to WAN point to point connection is also referred to as a serial connection or leased-line connection. Communications across a serial connection is a method of data transmissions in which the bits are transmitted sequentially over a single channel. This is equivalent to a pipe wide enough to fit one ball at a time. Serial and parallel ports: This is in contrast to parallel communications in which bits can be transmitted simultaneously over multiple wires. Parallel connection theoretically transfers data eight times faster than a serial connection. Based on this theory, a parallel connection sends a byte in the time that a serial connection sends a single bit. However, parallel communications do have issues with crosstalk across wires, especially as the wire length increases. Clock skew is also an issue with parallel communications. Clock skew occurs when the data across various wires does not arrive at the same time, creating synchronization issues. Finally, most parallel communications support only one-direction outbound-only communication from the hard drive. Serial Communication: Data is encapsulated by the communications protocol used by the sending router. The encapsulated frame is sent on a physical medium to the WAN. There are the various ways to traverse the WAN, but the receiving router uses the same communications protocol to de-encapsulate the frame when it arrives. There are three important serial communication standards affecting LAN-to-WAN connections: RS-232 – Most serial ports on personal computers confirm to the RS-232C or newer RS- 422 and RS-423 standards. Both 9-pin and 25-pin are used. A serial port is a general- purpose interface that can be used for almost any type of device, including modems, mice and printers. These types of peripheral devices for computers have been replaced by new and faster standards such as USB but many network devices use RJ-45 connectors. V.35 – Typically used for modem-to-multiplexer communication, this ITU standard for high speed, synchronous data exchange combines the bandwidth of several telephone circuits.
- 5. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 5 HSSI – A High-Speed Serial Interface (HSSI) supports transmission rates up to 52Mb/s. Point-to-Point Communication Links: When permanent dedicated connections are required, a point-to-point link is used to provide a single, pre-established WAN communications path from the customers premises, through the provider network, to a remote destination. A point-to-pint link can connect two geographically different sites, such as a cooperate office in New York and a reginal office in London. For a point to point line, the carrier dedicates specific resources for a line that is released by the customers (leased line). Point to point connections are not limited to connections that cross land. There are hundreds of thousands of miles of undersea fiber optic cables that connect countries and continents. The dedicated capacity removes latency or jitter between the endpoints, essential for some applications such as VoIP or video over IP. Time Division Multiplexing: Multiplexing refers to a scheme that allows multiple logical signals to share a single physical channel. Two common types of multiplexing are time-division multiplexing (TDM) and statistical Time-division multiplexing (STDM). Time Division Multiplexing (TDM): Bell Laboratories originally invented TDM to maximize the amount of voice traffic carried over a medium. Before multiplexing, each telephone call require its own physical link. This was an expensive and unscalable solution. TDM divides bandwidth of a single link into separate time slots. TDM transmits two or more channels (data stream) over the same link by allocating a different time slot for the transmission of each channel. In effect, the channels take turn using the link. Statistical Time-Division Multiplexing (STDM): In analogy, compare TDM to a train with 32 railroad cars. Each car is owned by a different company, and every day the train leaves with 32 cars attached. If one company has cargo to send, the car remains empty, but stays on the train. Shipping empty containers is not very efficient. TDM shares this inefficiency when traffic is intermittent, because the time slot is still allocated even when the channels has no data to transmit. STDM was developed to overcome this inefficiency. 1. STDM uses a variable time slot length allowing channels to compete for any free slot space. 2. It employs a buffer memory that temporarily stores the data during periods of peak traffic. STDM does not waste high speed line time with inactive channels using this scheme. STDM requires each transmission to carry identification information or a channel identifier. Demarcation Point: The demarcation point marks the point where your network interfaces with a network that is owned by another organization. DTE-DCE: From the point of view of connecting to the WAN, a serial connection has a DTE device at one end of the connection and a DCE device at the other end. The connection between two DCE devices is the WAN service provider transmission network. The DCE, commonly a modem or CSU/DSU, is the device used to convert the user data from the DTE into a form acceptable to the WAN service provider transmission link.
- 6. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 6 Serial Bandwidth: In North America, the bandwidth is usually expressed as a digital signal level number (DS0, DS1, etc.), which refers to the rate and format of the signal. The most fundamental line speed is 64 kb/s, or DS0, which is the bandwidth required for an uncompressed, digitized phone call. Serial connection bandwidth can be incrementally increased to accommodate the need for faster transmission. For example, 24 DS0s can be bundled to get a DS1 line (also called a T1 line) with a speed of 1.544 Mb/s. Also, 28 DS1s can be bundled to get a DS3 line (also called a T3 line) with a speed of 44.736 Mb/s. Leased lines are available in different capacities and are generally priced based on the bandwidth required and the distance. OC transmission rates are a set of standardized specifications for the transmission of digital signals carried on SONET fiber-optic networks. The designation uses OC, followed by an integer value representing the base transmission rate of 51.84 Mb/s. For example, OC-1 has a transmission capacity of 51.84 Mb/s, whereas an OC-3 transmission medium would be three times 51.84 Mb/s, or 155.52 Mb/s. HDLC Encapsulation: WAN Encapsulation Protocols: On each WAN connection, data is encapsulated into frames before crossing the WAN link. It insures the correct protocol is used, the appropriate Layer 2 encapsulation type must be configured. The following are short descriptions of WAN protocols: HDLC-The encapsulation type on point to point connections, dedicated links, and circuit- switched connections when the link uses two Cisco devices. HDLC is now the bases for synchronous PPP used by many servers to connect to a WAN, most commonly the Internet. PPP – Provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. PPP works with several network layer protocols, such as IPv4 and IPv6. PPP uses the HDLC encapsulation protocol, but also has a built-in security mechanism such as PAP and CHAP. Serial Line Internet Protocol (SLIP) – A standard protocol for point-to-point serial connections using TCP/IP. SLIP has been largely displaced by PPP. X.25/Link Access Procedure, Balanced (LAPB) – AnITU-T standard defines how connections between a DTE and DCE are maintained for remote terminal access and computer communications in public data networks. X.25 specifies LAPB, a data link layer protocol. X.25 is a procedure to Frame Relay. Frame Relay – An industry standard, switched, data link layer protocol that handle multiple virtual circuits. Frame Relay is next generation protocol after X.25. Frame Relay eliminates some of the time-consuming processes (such as error correction and flow control) employed in X.25. ATM – The international standard for cell relay in which devices send multiple service types, such as voice, video, or data, in fixed-length (53-byte) cell. HDLC Encapsulation: HDLC uses synchronous serial transmission to provide error-free communication between two points. HDLC defines a layer 2 framing structure that allows for flow control and error control through the use of acknowledgements. Each frame has the same
- 7. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 7 format, whether it is data format or control format. Cisco has developed an extension to the HDLC protocol to solve the inability to provide multiprotocol support. Although Cisco HDLC (also referred to as cHDLC) is proprietary, Cisco has allowed many other network equipment vendors to implement it. Cisco HDLC frames contain a field for identifying the network protocol being encapsulated. Dialup modem: Voice band modems are considered to be a legacy WAN technology. A voice band modem modulates (that is, converts) the digital signals produced by a computer into voice frequencies. These frequencies are then transmitted over the analog lines of the public telephone network. On the other side of the connection, another modem demodulates the sounds back into a digital signal for input to a computer or network connection. Access server: This server controls and coordinates dialup modem, dial-in, and dial-out user communications. Considered to be a legacy technology, an access server may have a mixture of analog and digital interfaces and support hundreds of simultaneous users. Broadband modem: This type of digital modem is used with high-speed DSL or cable Internet service. Both operate in a similar manner to the voice band modem but use higher broadband frequencies to achieve higher transmission speeds. Channel service unit/data service unit (CSU/DSU): Digital leased lines require a CSU and a DSU. A CSU/DSU can be a separate device like a modem, or it can be an interface on a router. The CSU provides termination for the digital signal and ensures connection integrity through error correction and line monitoring. The DSU converts the line frames into frames that the LAN can interpret and vice versa. WAN switch: This multiport internetworking device is used in service provider networks. These devices typically switch traffic, such as Frame Relay or ATM, and operate at Layer 2. Router: This device provides internetworking and WAN access interface ports that are used to connect to the service provider network. These interfaces may be serial connections, Ethernet, or other WAN interfaces. With some types of WAN interfaces, an external device, such as a DSU/CSU or modem (analog, cable, or DSL), is required to connect the router to the local service provider.
- 8. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 8 Q.No-3 How a PPP session is established using the functions of the LCP and NCPs. Also define how to ensure a secure PPP connection.? . Understanding PPP session establishment, LCP and NCP are important parts of implementing and troubleshooting PPP. These topics are discussed next. There are three phases of establishing a PPP session, Phase 1: Link establishment and configuration negotiation: Before PPP exchanges any network layer data grams, such as IP, the LCP must first open the connection and negotiate configuration options. This phase is complete when the receiving router sends a configuration-acknowledgment frame back to the router initiating the connection. Phase 2: Link quality determination (optional): The LCP tests the link to determine whether the link quality is sufficient to bring up network layer protocols. The LCP can delay transmission of network layer protocol information until this phase is complete. Phase 3: Network layer protocol configuration negotiation: After the LCP has finished the link quality determination phase, the appropriate NCP can separately configure the network layer protocols, and bring them up and take them down at any time. If the LCP closes the link, it informs the network layer protocols so that they can take appropriate action. The link remains configured for communications until explicit LCP or NCP frames close the link, or until some external event occurs such as an inactivity timer expiring, or an administrator intervening.
- 9. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 9 The LCP can terminate the link at any time. This is usually done when one of the routers requests termination, but can happen because of a physical event, such as the loss of a carrier or the expiration of an idle-period timer. PPP Security After you have completed installing PPP on every machine involved in your configuration, you can add either one or two levels of security for the PPP link. The first level, Password Authentication Protocol (PAP), is the least secure. A password is sent over the circuit "in the clear" until authentication is acknowledged or the connection terminated. The second level of security, Challenge-Handshake Authentication Protocol (CHAP), periodically verifies the identity of the peer--the other end of the point-to-point link. A challenge message is sent to the peer by the authenticator--the system starting the link or challenge. The response is checked against a "secret" not sent over the link, and if the values match, authentication is acknowledged. Otherwise, the link is terminated. Q.No-4 What are the pros and cons of using Frame Relay? Refer the following topology. Provide configuration commands for R1 and R2 to configure a Frame Relay connection. Advantages Cost Savings: FR offers reduction of physical local loops over private line network as frame uses a virtual circuit for each new connection Higher circuit utilization: FR makes use of physical circuit by statistically multiplexing multiple PVCs over a single physical circuit Higher network availability: FR network employs switches that support automatic routing of PVC around circuit failure Extended Technology Life Duration: FR is backwards compatible with older technologies like X.25 and forward compatible with newer technologies like ATM and MPLs Protocol Independence: Supports wide variety of application transports and meets the throughput requirements. Performance: FR services offers higher speed with lower delay as compared to X.25 Disadvantages 44.736 Mbps data rate is not enough for protocols with higher data rates Allows variable length frames Create varying delays for different users Not suitable for sending delay sensitive data such as real; time voice or video or teleconferencing.
- 10. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 10 Q.No-5 Differentiate between passive and active network attacks. What are the common types of attacks under both categories? The major difference between active and passive attacks is that in active attacks the attacker intercepts the connection and modifies the information. Whereas, in a passive attack, the attacker intercepts the transit information with the intention of reading and analyzing the information not for altering it. Active attacks are the attacks in which the attacker tries to modify the information or creates a false message. The prevention of these attacks is quite difficult because of a broad range of potential physical, network and software vulnerabilities. Instead of prevention, it emphasizes on the detection of the attack and recovery from any disruption or delay caused by it. Masquerade – Masquerade attack takes place when one entity pretends to be different entity. A Masquerade attack involves one of the other form of active attacks. Modification of messages – It means that some portion of a message is altered or that message is delayed or reordered to produce an unauthorized effect Repudiation This attack is done by either sender or receiver. The sender or receiver can deny later that he/she has send or receive a message Replay It involves the passive capture of a message and its subsequent the transmission to produce an authorized effect.
- 11. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 11 Denial of Service It prevents normal use of communication facilities. This attack may have a specific target. For example, an entity may suppress all messages directed to a particular destination. The active attacks are in the form of interruption, modification and fabrication. Interruption is known as masquerade attack in which unauthorized attacker tries to pose as another entity. Modification can be done using two ways replay attack and alteration. In the replay attack, a sequence of events or some data units is captured and resent by them. While alteration of the message involves some change to the original message, either one of them can cause alteration. Fabrication causes Denial Of Service (DOS) attacks in which attacker strive to prevent licit users from accessing some services, which they are permitted to or in simple words the attacker gain access to the network and then lock the authorized user out. Passive attacks are the attacks where the attacker indulges in unauthorized eavesdropping, just monitoring the transmission or gathering information. The eavesdropper does not make any changes to the data or the system. 1. The release of message content – Telephonic conversation, an electronic mail message or a transferred file may contain sensitive or confidential information. We would like to prevent an opponent from learning the contents of these transmissions. 2. Traffic analysis – Suppose that we had a way of masking (encryption) of information, so that the attacker even if captured the message could not extract any information from the message. The opponent could determine the location and identity of communicating host and could observe the frequency and length of messages being exchanged. This information might be useful in guessing the nature of the communication that was taking place. The active attacks are in the form of interruption, modification and fabrication. Interruption is known as masquerade attack in which unauthorized attacker tries to pose as another entity. Modification can be done using two ways replay attack and alteration. In the replay attack, a sequence of events or some data units is captured and resent by them. While alteration of the message involves some change to the original message, either one of them can cause alteration.
- 12. DEPARTMENT OF INFORMATION TECHNOLOGYQUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGYNAWABSHAH, SINDH 16 BS (IT) 05 Page 12 Fabrication causes Denial Of Service (DOS) attacks in which attacker strive to prevent licit users from accessing some services, which they are permitted to or in simple words the attacker gain access to the network and then lock the authorized user out.