Bluetooth, WiMAX, RFID, and Mobile Communications PDF

Chapter 4-4 Bluetooth, WiMAX, RFID, and Mobile Commununicatons  Introduction This section looks at three different wireless technologies. These include Bluetooth, WiMAX, and RFID. Each of these technologies play important roles in the wireless networks. This sec...

Chapter 4-4 Bluetooth, WiMAX, RFID, and Mobile Commununicatons  Introduction This section looks at three different wireless technologies. These include Bluetooth, WiMAX, and RFID. Each of these technologies play important roles in the wireless networks. This section examines each of these wireless technologies including a look at configuration and examples of the hardware being used.  Bluetooth This section examines Bluetooth which is based on the 802.15 standard.. Bluetooth was developed to replace the cable connecting computers, mobile phones, handheld devices, portable computers, and fixed electronic devices. The information is transmitted over the 2.4 GHz ISM frequency band which is the same frequency band used by 802.11b,g,n. There are three output power classes for Bluetooth.  Inquiry Procedure When a Bluetooth device is enabled, it uses an inquiry procedure to determine if any other Bluetooth devices are available. This procedure is also used to allow itself to be discovered.  Bluetooth If a Bluetooth device is discovered, it sends an inquiry reply back to the Bluetooth device initiating the inquiry. Next, the Bluetooth devices enter the paging procedure. The paging procedure is used to establish and synchronize a connection between two Bluetooth devices. Once the procedure for establishing the connection has been completed, the Bluetooth devices will have established a piconet. A piconet is an ad hoc network of up to eight Bluetooth devices such as a computer, mouse, headset, earpiece, etc. In a piconet, one Bluetooth device (the master) is responsible for providing the synchronization clock reference. All other Bluetooth devices are called slaves.  WiMAX WiMAX (Worldwide Interoperability for Microwave Access) is a broadband wireless system and has been developed for use as broadband wireless access (BWA) for fixed and mobile stations and will be able to provide a wireless alternative for last mile broadband access in the 2 GHz to 66 GHz frequency range. BWA access for fixed stations can be up to 30 miles while mobile BWA access is 3-10 miles. Internationally, the WiMAX frequency standard will be 3.5 GHz while the United States will use both the unlicensed 5.8 GHz and the licensed 2.5 GHz spectrum.  WiMAX WiMAX also provides flexible channel sizes (e.g. 3.5 MHz, 5 MHz, and 10 MHz) which provides adaptability to standards for WiMAX worldwide. This also helps to ensure that the maximum data transfer rate is being supported. For example, the allocated channel bandwidth could be 6 MHz and the adaptability of the WiMAX channel size allows it to adjust to use the entire allocated bandwidth.  WiMAX The WiMAX (IEEE 802.16e) media access control (MAC) layer differs from the IEEE 802.11 Wi-Fi MAC layer in that the WiMAX system only has to compete once to gain entry into the network. Once a WiMAX unit has gained access, it is allocated a time slot by the base station thereby providing the WiMAX with scheduled access to the network. WiMAX operates in a collision free environment which improves channel throughput.  WiMAX WiMAX has a range of up to 31 miles and it operates in both point-to-point point-to-multipoint configurations. This can be useful in situations where DSL or cable network connectivity is not available. WiMAX is also useful for providing the last mile connection. The last mile is basically the last part of the connection from the telecommunications provider to the customer. The cost of the last mile connection can be expensive which makes a wireless alternative attractive to the customer.  RFID RFID – Radio Frequency Identification is a technique that uses radio waves to track and identify people, animal, objects, and shipments. This is done by the principle of modulated backscatter. The term “backscatter” is referring to the reflection of the radio waves striking the RFID tag and reflecting back to the transmitter source with its stored unique identification information.  RFID System The RFID system consists of two things: - RFID tag (also called the RF transponder) which includes an integrated antenna and radio electronics - Reader (also called a transceiver which consists of a transceiver and an antenna. A transceiver is the combination of a transmitter and receiver. The reader (transceiver) transmits radio waves which activates (turns on) an RFID tag. The tag then transmits modulated data, containing its unique identification information stored in the tag, back to the reader. The reader then extracts the data stored on the RFID tag. RFID Tag  RFID System There are three parameters that define an RFID system. These include the following: Means of powering the tag Frequency of operation Communications protocol (also called the air interface protocol)  Powering the Taq RFID tags are classified in three ways based on how they obtain their operating power. The three different classifications are passive, semi-active, and active. Passive: Power is provided to the tag by rectifying the RF energy, transmitted from the Reader, that strikes the RF tag antenna. The rectified power level is sufficient to power the ICs on the tags and also provides sufficient power for the tag to transmit a signal back to the reader. Semi-active: The tags use a battery to power the electronics on the tag but use the property of backscatter to transmit information back to the reader. Active: Use a battery to power the tag and transmit a signal back to the reader. Basically this is a radio transmitter. New active RFID tags are incorporating wireless Ethernet, the 802.11b – WiFi connectivity.  Frequency of Operation The RFID tags must be tuned to the reader’s transmit frequency to turn on. RFID systems typically use three frequency bands for operation, LF, HF, and UHF as shown in Figure 11-24: Low Frequency (LF) tags typically use frequency-shift keying (FSK) between the 125/134 kHz frequencies. The data rates from these tags is low (~12 kbps) and they are not appropriate for any applications requiring fast data transfers. However, the low frequency tags are suitable for animal identification such as dairy cattle and other livestock. The read range for low frequency tags is approximately.33 meters.  Frequency of Operation High Frequency (HF) tags operate in the 13.56 MHz industrial band. It is known that the longer wavelengths of the HF radio signal are less susceptible to absorption by water or other liquids. Therefore, these tags are better suited for tagging liquids. The read range for high frequency tags is approximately 1 meter. The short read range provides for better defined read ranges. The applications for tags in this frequency range include access control, smart cards, and shelf inventory. The data rate for high frequency (HF) tags is 26 kbps  Frequency of Operation Ultra-high frequency (UHF) tags work at 860-960 MHz and at 2.4 GHz. The data rates for these tags can be from 50-150 kbps and greater. These tags are popular for tracking inventory. The read range for passive UHF tags is 10 – 20 ft which make it a better choice for reading pallet tags. However, if an active tag is used, a read range up to 100 meters is possible.  Communication Protocol The air interface protocol adopted for RFID tags is Slotted Aloha a network communications protocol technique similar to the Ethernet protocol. In a Slotted Aloha protocol, the tags are only allowed to transmit at pre-determined times after being energized. This technique reduces the chance of data collisions between RFID tag transmissions and allows for the reading of up to 1000 tags per second. The operating range for RFID tags can be up to 30 meters. This means that multiple tags can be energized at the same time and a possible RF data collision can occur. If a collision occurs, the tag will transmit again after a random back- off time. The readers transmit continuously until there is no tag collision.  Mobile Communications This is a brief summary of the some of the other wireless technologies currently available. CDMA – Code Division Multiple Access This is a communications system in which spread-spectrum techniques are used to multiplex more than one signal within a single channel. LTE – Long Tem Evolution is a 4G Wireless communications standard. It has been designed to provide up to 10 times 3G network speeds  Mobile Communications HSPA+ (Evolved High-Speed Packet Access) has been developed to provide network speeds comparable to LTE networks. Theoretical speeds for download are said to be 168Mbps and uplink of 22Mbps. 3G/4G was developed to provide broadband network wireless services. The standard defining 3G wireless is called international mobile communications, or IMT 2000. 4G (fourth generation) is the successor to 3G technology and it provides download speeds of 100 Mbps. Edge (Enhanced Data GSM Evolution) provides download speeds of 384 Kbps.  Chapter 4-4 Key Terms inquiry procedure paging procedure piconet last mile backscatter RFID tag reader Slotted Aloha  Chapter 4-5 Configuring a Point-to-Point Wireless LANs A Case Study  Introduction This section presents an example of preparing a proposal for providing a point-to-multipoint wireless network for a company. The administrators for the company have decided that it would be beneficial to provide a wireless network connection for their employees back to the company’s network (Home network).  Overview This example problem addresses the following issues: I. conducting an initial antenna site survey II. establishing a link from the home network to the distribution point III. configuring the multipoint distribution IV. conducting an RF site survey for the establishing a baseline signal level for the remote wireless user V. configuring the remote user’s installation  I. Antenna Site Survey The proposed antenna site is on top of a hill approximately 1 km from the home network. A site survey of the proposed antenna site provided the following information. the site has a tower that can be used to mount the wireless antenna  I. Antenna Site Survey the site has a small building and available rack space for setting up the wireless networking equipment there is a clear view of the surrounding area for 6 km in any direction there is not an available wired network connection back to the home network.  II. Establishing a Point-to-Point Wireless Link to the Home Network Issue: Cost of the link to the home network  Antenna Selection Three possible antennas were selected for the wireless network. These are provided in Table 4-4. Table 4-4 A sample of 802.11b wireless antennas Antenna Radiation Pattern Range km Costs Type 2 Mbps 11 Mbps Omni omni-directional 7 2 moderate Yagi directional 12 7.5 moderate Dish highly directional 38 18 high  Antenna Selection Antenna A has an omni-directional radiation pattern. This means that the antenna can receive and transmit signals in a 360o pattern.  Antenna Selection Antenna B is a Yagi antenna with a directional radiation pattern as shown. The cost of the Yagi antenna is comparable to the omni-directional antenna.  Antenna Selection Antenna C is a “dish” antenna or parabolic reflector. These antennas provide extremely high directional gain. The cost of the dish antenna can be quite high relative to the cost of the Yagi or omni-directional antenna. Sector Antenna Dish Parabolic Yagi Omni  III. Configuring the Antenna Site for Multipoint Distribution At this point, an 11 Mbps wireless data link has been established with the home network. The next task is to configure the antenna site for multipoint distribution. It was previously decided that a 2 Mbps link would be adequate for the remote users. This decision was based on the data rate to be supported for the planned coverage area. The site survey in step I showed that there is a clear view of the surrounding area for 12 km, 6 km is each direction. Antenna A (Table 4-4) provides an omni- directional radiation pattern for 7 km. This satisfies that coverage area and 2 Mbps data rate.  Configuring the Site Antenna A (omni-directional) was mounted on the antenna site tower. An RF site survey of the planned coverage area was next done to verify the signal quality provided by the antenna selected. Measurements were made from multiple locations within the planned coverage area. IV. Site Survey IV. Site Survey  V. Configuring the remote installations The antenna for the remote user only needs to be able to see the multi-point distribution antenna site. The requirements for the remote client are as follows: - 2 Mbps data rate connection directional antenna (Yagi) plus mount, lightening arrestor, wireless bridge Antenna B (Yagi) was selected for the directional antenna. This antenna will provide sufficient RF signal level for the remote user. Each remote user will need a wireless bridge, and a switch to connect multiple users. Note: the bridge is set for a 2 Mbps data rate. The set-up for the remote user is shown.  Chapter 4 Summary This chapter has presented an overview of wireless networking. The vendors of wireless networking equipment have made the use of wireless networks very easy to integrate into existing networks. But the reader must understand that the key objective of the network administrator is to provide a fast, reliable, and secure computer network. Carelessly integrating wireless components into the network can easily compromise this objective.  Chapter 4 Summary The concepts the student should understand from reading this chapter are: The operating characteristics of the 802.11 wireless networks The purpose of access points, wireless LAN adapters, and wireless bridges How to perform a basic site survey on a building How to configure the network for user mobility How to plan a multipoint wireless distribution  Ch. 4 Summary A final note, the new wireless networking technologies have greatly simplified the planning and installation. Anytime you are working with RF (Radio-frequencies) there is a chance of unexpected interference and noise. A well-planned RF installation requires a study of all known and a search for any possible interferences. An RF study will also include signal path studies that enable the user to prepare a well thought-out plan and allow an excellent prediction of received signal level. The bottom-line is to obtain support for conducting an RF study if needed.  Chapter 4-6 Troubleshooting Wireless Networks  Troubleshooting This section examines some common techniques for troubleshooting wireless networks. Wireless networks have greatly simplified the steps for connecting to a network but wireless networks do occasionally fail. The following are some scenarios that the user might encounter and outlines steps for troubleshooting and resolving the wireless issues.  Troubleshooting Hardware Issues Your primary hardware device in wireless networks is the access point. In some cases you might have multiple access points. A simple first step is to ping the IP address for the access point. The purpose of the ping is to verify you have network connectivity. If the ping doesn’t work then try unplugging the access point and then plug it back in. This resets the access point.  Troubleshooting Signal Strength Problems The purpose of measuring the signal strength is to verify that you have “good” signal level at the receive location. Things change and a loss in signal strength might not be a problem with the access point. It is possible that something could have been moved and is physically blocking the signal.  Troubleshooting Frequency Interference There might also be an electrical device such as a microwave oven that could be causing interference. Microwave ovens operate at the frequency of 2.4GHz, which is the same band as 802.11b/g/n devices. It is always good to have a baseline measurement of the signal strength expected at each location for situations such as this.  Troubleshooting Load Issues Wireless users share the same frequency channel to communicate to same access point. If too many users are connecting at the same time to the same access point, they will start experiencing slowness and packet drops. For the optimum load capacity, one should consult the documentation of the access point manufacture.  Troubleshooting DHCP Issues Your access points typically assign a 192.168.0.x address to the client. You can verify the IP address assigned by entering the command ipconfig from the command prompt  Troubleshooting SSID Issues Once the SSID (Service Set Identifier) has been configured for a computer then this normally does not require re-configuration. However, in your travels, you might have re-configured the SSID to connect to a different network. The simple fix is the reset your SSID when you return to your home network.  Troubleshooting Securing Wi-Fi Most wireless systems support multiple network security protocols e.g. different versions of WPA/WEP. Make sure the client and access point are running the same security mode. Anytime you are connecting your wireless device to a public hot spot there is a chance that someone using a packet sniffer can see you data traffic. You can avoid possible problems by enabling WPA to secure your data traffic.  Troubleshooting Selecting Wireless Channels The default channel for 802.11b and 802.11g routers is channel 6. If you have interference problems then you can change the channel to 1 or 11. The RF spectrum on these channels do not overlap. (see Figure 4-4 in Chapter 4, “Wireless Networking”). This will most likely solve your problem. 802.11b and 802.11g wireless routers have 11 possible channels and selection of an alternate channel is managed via the wireless router’s setting  Troubleshooting Extending the Wireless Range Make sure your antenna is placed high and not obstructed by any metal. It is important to remember that radio waves will reflect off metal surfaces. Also, surfaces such as concrete and brick will attenuate the signal. In some cases you might have to use a high gain antenna to help boost your receive signal strength.  Troubleshooting Selecting Wireless Channels The default channel for 802.11b and 802.11g routers is channel 6. If you have interference problems then you can change the channel to 1 or 11. The RF spectrum on these channels do not overlap. This will most likely solve your problem. 802.11b and 802.11g wireless routers have 11 possible channels and selection of an alternate channel is managed via the wireless router’s setting  Troubleshooting Wireless Compatibility Not all wireless clients are created equal as wireless clients depend on their hardware and software. Also, in order to have reliable and good throughput wireless connectivity, both the wireless access point and the wireless clients must be compatible and use the same standard. 802.11n is a standard that can offer connectivity in either 2.4GHz or 5GHz or both. This means a wireless client can be 802.11n compatible just by operating in one frequency not both.  Troubleshooting Cable Issues Even though you are focusing on troubleshooting wireless issues, sometimes the problem could be due to a simple physical cable connection. The cable could be loose or has become disconnected or the cable is bad. It is always good to have a spare cable just in case. Remember, you can always verify you have a connection by checking for the presence of a link light!  Troubleshooting Switch Uptime A common task for the network technician is to verify the uptime for a switch. This will help identify potential problems with switches that might be intermittently resetting. The command for viewing the switch uptime is switch#show version. The reason to check the uptime is to see if a switch has been rebooting. Rebooting problems can be due to power fluctuations or a switch problem. In either case the network technician will need to know how to identify this problem and propose a solution. Chapter 6-2 the TCP/IP Layers  the TCP/IP Layers The four layers of the TCP/IP model are listed in Table 6-1. The layers are Application Internet Transport Network Interface  the TCP/IP Layers The TCP/IP protocol was established in 1978, prior to the final release of the OSI model (see Chapter 4) however, the four layers of the TCP/IP model do correlate to the seven layers of the OSI model as shown in the next slide (Fig. 6-1). The Application layer of the TCP/IP stack is responsible for making sure a connection is made to an appropriate network port. These ports are reserved by ICANN (Internet Corporation for Assigned Names and Numbers).  Transport Layer The transport layer protocols in TCP/IP are very important in establishing a network connection, managing the delivery of data between a source and destination host, and terminating the data connection. There are two transport protocols within the TCP/IP transport layer. These are TCP and UDP. The first protocol examined is TCP. TCP, the Transport Control Protocol is a connection oriented protocol. A connection oriented protocol establishes the network connection, manages the data transfer, and terminates the connection. The TCP protocol establishes a set of rules or guidelines for establishing the connection. TCP verifies the delivery of the data packets through the network and includes support for error checking and recovering lost data. TCP then specifies a procedure for terminating the network connection. There is a unique sequence of three data packets exchanged at the beginning of a TCP connection between two hosts. A connection between two hosts is shown. This is a virtual connection that is made over the network. The first three packets always exchanged between two hosts when establishing a TCP connection are: the SYN (Synchronizing) packet the SYN + ACK (Synchronizing + Acknowledgement) packet the ACK (Acknowledgement) packet The three-packet initial TCP handshake The following is a example of a TCP packet transmission captured using a protocol analyzer. The network is set-up as shown. Host A (the client) is establishing an FTP connection with Host B. The captured file is 5-a.cap and is provided on the CD-ROM in the capture folder. Portions of the captured data packets are next shown.  the three packets exchanged in the initial TCP handshake. Packet 1 (ID 000001) is called the “SYN” or synchronizing packet. This packet is sent from the host computer on the network that wants to establish a TCP network connection. In this example, host A is making a TCP connection for an FTP file transfer. The summary information for packet 1 specifies that this is a TCP packet, the source port is 1054 (SP=1054), and the destination port is 21 (DP=21).  the three packets exchanged in the initial TCP handshake. Packet 1 (ID 000001) is called the “SYN” or synchronizing packet. This packet is sent from the host computer on the network that wants to establish a TCP network connection. In this example, host A is making a TCP connection for an FTP file transfer. The summary information for packet 1 specifies that this is a TCP packet, the source port is 1054 (SP=1054), and the destination port is 21 (DP=21).  the three packets exchanged in the initial TCP handshake. Packet 1 (ID 000001) is called the “SYN” or synchronizing packet. This packet is sent from the host computer on the network that wants to establish a TCP network connection. In this example, host A is making a TCP connection for an FTP file transfer. The summary information for packet 1 specifies that this is a TCP packet, the source port is 1054 (SP=1054), and the destination port is 21 (DP=21).  the three packets exchanged in the initial TCP handshake. Packet 1 (ID 000001) is called the “SYN” or synchronizing packet. This packet is sent from the host computer on the network that wants to establish a TCP network connection. In this example, host A is making a TCP connection for an FTP file transfer. The summary information for packet 1 specifies that this is a TCP packet, the source port is 1054 (SP=1054), and the destination port is 21 (DP=21).  the three packets exchanged in the initial TCP handshake. Packet 1 (ID 000001) is called the “SYN” or synchronizing packet. This packet is sent from the host computer on the network that wants to establish a TCP network connection. In this example, host A is making a TCP connection for an FTP file transfer. The summary information for packet 1 specifies that this is a TCP packet, the source port is 1054 (SP=1054), and the destination port is 21 (DP=21).  the three packets exchanged in the initial TCP handshake. Packet 1 (ID 000001) is called the “SYN” or synchronizing packet. This packet is sent from the host computer on the network that wants to establish a TCP network connection. In this example, host A is making a TCP connection for an FTP file transfer. The summary information for packet 1 specifies that this is a TCP packet, the source port is 1054 (SP=1054), and the destination port is 21 (DP=21).  the three packets exchanged in the initial TCP handshake. Port 1054 is an arbitrary port number that the FTP client picks or is assigned by the operating system. The destination port 21 is the well-known FTP (see. Table 6-3). The packet has a starting sequence number SEQ=997462768, and there is no acknowledgement (ACK=0). The length of the data packet is 0 (LEN=0). This indicates that the packet does not contain any data. The window size = 16384 (WS=16384). The window size indicates how many data packets can be transferred without an acknowledgement.  the three packets exchanged in the initial TCP handshake. Port 1054 is an arbitrary port number that the FTP client picks or is assigned by the operating system. The destination port 21 is the well-known FTP (see. Table 6-3). The packet has a starting sequence number SEQ=997462768, and there is no acknowledgement (ACK=0). The length of the data packet is 0 (LEN=0). This indicates that the packet does not contain any data. The window size = 16384 (WS=16384). The window size indicates how many data packets can be transferred without an acknowledgement.  the three packets exchanged in the initial TCP handshake. Port 1054 is an arbitrary port number that the FTP client picks or is assigned by the operating system. The destination port 21 is the well-known FTP (see. Table 6-3). The packet has a starting sequence number SEQ=997462768, and there is no acknowledgement (ACK=0). The length of the data packet is 0 (LEN=0). This indicates that the packet does not contain any data. The window size = 16384 (WS=16384). The window size indicates how many data packets can be transferred without an acknowledgement.  the three packets exchanged in the initial TCP handshake. Port 1054 is an arbitrary port number that the FTP client picks or is assigned by the operating system. The destination port 21 is the well-known FTP (see. Table 6-3). The packet has a starting sequence number SEQ=997462768, and there is no acknowledgement (ACK=0). The length of the data packet is 0 (LEN=0). This indicates that the packet does not contain any data. The window size = 16384 (WS=16384). The window size indicates how many data packets can be transferred without an acknowledgement.  the three packets exchanged in the initial TCP handshake. Port 1054 is an arbitrary port number that the FTP client picks or is assigned by the operating system. The destination port 21 is the well-known FTP (see. Table 6-3). The packet has a starting sequence number SEQ=997462768, and there is no acknowledgement (ACK=0). The length of the data packet is 0 (LEN=0). This indicates that the packet does not contain any data. The window size = 16384 (WS=16384). The window size indicates how many data packets can be transferred without an acknowledgement.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 2 is the “SYN-ACK” packet from the FTP server. The sequence number SEQ = 3909625466 is the start of a new sequence number for the data packet transfers from host B. The source port is 21 (SP=21) and the destination port for packet 2 is 1054 (DP=1054). ACK=997462769 is an acknowledge by host B (the FTP server) that the first TCP transmission was received. Note that this acknowledgement shows an increment of one from the starting sequence number provided by host A in packet 1.  the three packets exchanged in the initial TCP handshake. Packet 3 is an acknowledgement from the client (host A) back to the FTP server (host B) that packet 2 was received. Note the acknowledgement is ACK= 3909625467 which is an increment of one from the SEQ number transmitted is packet 2. This completes the initial handshake establishing the TCP connection. The next part is the data packet transfer. At this point, the two hosts can begin transferring data packets.  the three packets exchanged in the initial TCP handshake. Packet 3 is an acknowledgement from the client (host A) back to the FTP server (host B) that packet 2 was received. Note the acknowledgement is ACK= 3909625467 which is an increment of one from the SEQ number transmitted is packet 2. This completes the initial handshake establishing the TCP connection. The next part is the data packet transfer. At this point, the two hosts can begin transferring data packets.  the three packets exchanged in the initial TCP handshake. Packet 3 is an acknowledgement from the client (host A) back to the FTP server (host B) that packet 2 was received. Note the acknowledgement is ACK= 3909625467 which is an increment of one from the SEQ number transmitted is packet 2. This completes the initial handshake establishing the TCP connection. The next part is the data packet transfer. At this point, the two hosts can begin transferring data packets.  the three packets exchanged in the initial TCP handshake. Packet 3 is an acknowledgement from the client (host A) back to the FTP server (host B) that packet 2 was received. Note the acknowledgement is ACK= 3909625467 which is an increment of one from the SEQ number transmitted is packet 2. This completes the initial handshake establishing the TCP connection. The next part is the data packet transfer. At this point, the two hosts can begin transferring data packets.  the three packets exchanged in the initial TCP handshake. Packet 3 is an acknowledgement from the client (host A) back to the FTP server (host B) that packet 2 was received. Note the acknowledgement is ACK= 3909625467 which is an increment of one from the SEQ number transmitted is packet 2. This completes the initial handshake establishing the TCP connection. The next part is the data packet transfer. At this point, the two hosts can begin transferring data packets.  Terminating the TCP Session The last part of the TCP connection is terminating the session for each host. The first thing that happens is a host sends a FIN (finish) packet to the other connected host. Host B sends a FIN packet to Host A indicating the data transmission is complete. Host A responds with an ACK packet acknowledging the reception of the FIN packet. Host A then sends Host B a FIN packet indicating that the connection is being terminated. Host B replies with an ACK packet.  An example of the four-packet TCP connection termination. Packet 48 is a TCP packet with a source port of 21 (SP=21) and a destination port of 1054 (DP= 1054). The FIN statement is shown followed by a SEQ# and an ACK#. Remember, the SEQ and ACK numbers are used to keep track of the number of packets transmitted and an acknowledgement of the number received. The LEN of packet 48 is 0 which means the packet does not contain any data.  An example of the four-packet TCP connection termination. Packet 48 is a TCP packet with a source port of 21 (SP=21) and a destination port of 1054 (DP= 1054). The FIN statement is shown followed by a SEQ# and an ACK#. Remember, the SEQ and ACK numbers are used to keep track of the number of packets transmitted and an acknowledgement of the number received. The LEN of packet 48 is 0 which means the packet does not contain any data.  An example of the four-packet TCP connection termination. Packet 48 (Fig. 6-7) is a TCP packet with a source port of 21 (SP=21) and a destination port of 1054 (DP= 1054). The FIN statement is shown followed by a SEQ# and an ACK#. Remember, the SEQ and ACK numbers are used to keep track of the number of packets transmitted and an acknowledgement of the number received. The LEN of packet 48 is 0 which means the packet does not contain any data.  An example of the four-packet TCP connection termination. Packet 48 (Fig. 6-7) is a TCP packet with a source port of 21 (SP=21) and a destination port of 1054 (DP= 1054). The FIN statement is shown followed by a SEQ# and an ACK#. Remember, the SEQ and ACK numbers are used to keep track of the number of packets transmitted and an acknowledgement of the number received. The LEN of packet 48 is 0 which means the packet does not contain any data.  An example of the four-packet TCP connection termination. Packet 48 (Fig. 6-7) is a TCP packet with a source port of 21 (SP=21) and a destination port of 1054 (DP= 1054). The FIN statement is shown followed by a SEQ# and an ACK#. Remember, the SEQ and ACK numbers are used to keep track of the number of packets transmitted and an acknowledgement of the number received. The LEN of packet 48 is 0 which means the packet does not contain any data.  An example of the four-packet TCP connection termination. Packet 48 (Fig. 6-7) is a TCP packet with a source port of 21 (SP=21) and a destination port of 1054 (DP= 1054). The FIN statement is shown followed by a SEQ# and an ACK#. Remember, the SEQ and ACK numbers are used to keep track of the number of packets transmitted and an acknowledgement of the number received. The LEN of packet 48 is 0 which means the packet does not contain any data.  An example of the four-packet TCP connection termination. Packet 49 is an acknowledgement from the host, at port 1054, of the FIN packet. Remember the FIN packet was sent by the Host at the source port 21. In packet 50 the Host at port 1054 sends a FIN packet to the host at the destination port of 21. In packet 51, the host at port 21 acknowledges the reception of the FIN packet and the four packet sequence closes the TCP connection.  An example of the four-packet TCP connection termination. Packet 49 is an acknowledgement from the host, at port 1054, of the FIN packet. Remember the FIN packet was sent by the Host at the source port 21. In packet 50 the Host at port 1054 sends a FIN packet to the host at the destination port of 21. In packet 51, the host at port 21 acknowledges the reception of the FIN packet and the four packet sequence closes the TCP connection.  An example of the four-packet TCP connection termination. Packet 49 is an acknowledgement from the host, at port 1054, of the FIN packet. Remember the FIN packet was sent by the Host at the source port 21. In packet 50 the Host at port 1054 sends a FIN packet to the host at the destination port of 21. In packet 51, the host at port 21 acknowledges the reception of the FIN packet and the four packet sequence closes the TCP connection.  An example of the four-packet TCP connection termination. Packet 49 is an acknowledgement from the host, at port 1054, of the FIN packet. Remember the FIN packet was sent by the Host at the source port 21. In packet 50 the Host at port 1054 sends a FIN packet to the host at the destination port of 21. In packet 51, the host at port 21 acknowledges the reception of the FIN packet and the four packet sequence closes the TCP connection.  An example of the four-packet TCP connection termination. Packet 49 is an acknowledgement from the host, at port 1054, of the FIN packet. Remember the FIN packet was sent by the Host at the source port 21. In packet 50 the Host at port 1054 sends a FIN packet to the host at the destination port of 21. In packet 51, the host at port 21 acknowledges the reception of the FIN packet and the four packet sequence closes the TCP connection.  An example of the four-packet TCP connection termination. Packet 49 is an acknowledgement from the host, at port 1054, of the FIN packet. Remember the FIN packet was sent by the Host at the source port 21. In packet 50 the Host at port 1054 sends a FIN packet to the host at the destination port of 21. In packet 51, the host at port 21 acknowledges the reception of the FIN packet and the four packet sequence closes the TCP connection.  UDP UDP, the User Datagram Protocol is a connectionless protocol. This means that UDP packets are transported over the network without a connection being established and without any acknowledgement that the data packets arrived at the destination. UDP is useful in applications such as videoconferencing and audio feeds where acknowledgements that the data packet arrived are not necessary.  A UDP packet transfer Packet 136 is the start of a UDP packet transfer of an Internet audio feed. A TCP connection to the Internet was first made and then the music feed was started. At that time, the UDP connectionless packets started.  A UDP packet transfer Packet 136 is the start of a UDP packet transfer of an Internet audio feed. A TCP connection to the Internet was first made and then the music feed was started. At that time, the UDP connectionless packets started.  A UDP packet transfer Packets 138, 139, and 140 are the same type of packets with a length of 789. There are no acknowledgements sent back from the client. All of the packets are coming from the Internet source. UDP does not have a procedure for terminating the data transfer, the source either stops delivery of the data packets or the client terminates the connection.  A UDP packet transfer Packets 138, 139, and 140 are the same type of packets with a length of 789. There are no acknowledgements sent back from the client. All of the packets are coming from the Internet source. UDP does not have a procedure for terminating the data transfer, the source either stops delivery of the data packets or the client terminates the connection.  A UDP packet transfer Packets 138, 139, and 140 are the same type of packets with a length of 789. There are no acknowledgements sent back from the client. All of the packets are coming from the Internet source. UDP does not have a procedure for terminating the data transfer, the source either stops delivery of the data packets or the client terminates the connection.  The Internet Layer The TCP/IP Internet Layer defines the protocols used for address and routing the data packets. Protocols that are part of the TCP/IP Internet layer include IP, ARP, ICMP, and IGMP.  IP (Internet Protocol) IP, the Internet Protocol, defines the addressing used for identifying the source and destination addresses of data packets being delivered over an IP network. The IP address is a logical address that consists of a network and a host address portion. The network portion is used to direct the data to the proper network. The host address identifies the address locally assigned to the host. The network portion of the address is similar to the area code for a telephone number. The host address in similar to the local exchange number. The network and host portions of the IP address are then used to route the data packets to the destination.  ARP (Address Resolution Protocol) ARP, the Address Resolution Protocol, is used to resolve an IP address to a hardware address for final delivery of data packets to the destination. ARP issues a query in a network called an ARP request, asking which network interface has this IP address. The host assigned the IP address replies with an ARP reply that contains the hardware address for the destination host. As shown highlighted in blue, an ARP request is issued on the LAN. The source MAC address of the packet is 00-10-A4-13-99-2E. The destination address on the local area network shown is BROADCAST which means that this message is being sent to all computers in the local area network. A query (Q) is being asked who has the IP address 10.10.10.1 (PA= ). PA is an abbreviation for Protocol Address. As shown highlighted in blue, an ARP request is issued on the LAN. The source MAC address of the packet is 00-10-A4-13-99-2E. The destination address on the local area network shown is BROADCAST which means that this message is being sent to all computers in the local area network. A query (Q) is being asked who has the IP address 10.10.10.1 (PA= ). PA is an abbreviation for Protocol Address. As shown highlighted in blue, an ARP request is issued on the LAN. The source MAC address of the packet is 00-10-A4-13-99-2E. The destination address on the local area network shown is BROADCAST which means that this message is being sent to all computers in the local area network. A query (Q) is being asked who has the IP address 10.10.10.1 (PA= ). PA is an abbreviation for Protocol Address. As shown highlighted in blue, an ARP request is issued on the LAN. The source MAC address of the packet is 00-10-A4-13-99-2E. The destination address on the local area network shown is BROADCAST which means that this message is being sent to all computers in the local area network. A query (Q) is being asked who has the IP address 10.10.10.1 (PA= ). PA is an abbreviation for Protocol Address. The highlighted blue area now shows the destination computer replying with its MAC address back to the source that issued the ARP request. This is called an ARP reply which is a protocol where the MAC address is returned. The R after the ARP indicates this is an ARP reply. The source of the ARP reply is from 00-10-A4-13-6C-6E which is replying that the MAC address for 10.10.10.1 is 00-10-A4-13-6C-6E (HA=). In this case, the owner of the IP address replied to the message but this is not always the case. In some cases another networking device such as a router can provide the MAC address information. In that case, the MAC address being returned is for the next networking device in the route to the destination. The highlighted blue area now shows the destination computer replying with its MAC address back to the source that issued the ARP request. This is called an ARP reply which is a protocol where the MAC address is returned. The R after the ARP indicates this is an ARP reply. The source of the ARP reply is from 00-10-A4-13-6C-6E which is replying that the MAC address for 10.10.10.1 is 00-10-A4-13-6C-6E (HA=). In this case, the owner of the IP address replied to the message but this is not always the case. In some cases another networking device such as a router can provide the MAC address information. In that case, the MAC address being returned is for the next networking device in the route to the destination. The highlighted blue area now shows the destination computer replying with its MAC address back to the source that issued the ARP request. This is called an ARP reply which is a protocol where the MAC address is returned. The R after the ARP indicates this is an ARP reply. The source of the ARP reply is from 00-10-A4-13-6C-6E which is replying that the MAC address for 10.10.10.1 is 00-10-A4-13-6C-6E (HA=). In this case, the owner of the IP address replied to the message but this is not always the case. In some cases another networking device such as a router can provide the MAC address information. In that case, the MAC address being returned is for the next networking device in the route to the destination. The highlighted blue area now shows the destination computer replying with its MAC address back to the source that issued the ARP request. This is called an ARP reply which is a protocol where the MAC address is returned. The R after the ARP indicates this is an ARP reply. The source of the ARP reply is from 00-10-A4-13-6C-6E which is replying that the MAC address for 10.10.10.1 is 00-10-A4-13-6C-6E (HA=). In this case, the owner of the IP address replied to the message but this is not always the case. In some cases another networking device such as a router can provide the MAC address information. In that case, the MAC address being returned is for the next networking device in the route to the destination. the packet details of the ARP request  ICMP Protocol ICMP, the Internet Control Message Protocol is used to control the flow of data in the network , reporting errors, and for performing diagnostics. A networking device, such as a router, sends an ICMP source-quench packet to a host that requests a slowdown in the data transfer. A very important troubleshooting tool within the ICMP protocol is PING, the Packet InterNet Groper. The ping command is used to verify connectivity with another host in the network. The destination host could be in a LAN, a campus LAN, or on the Internet.  IGMP Protocol IGMP is the Internet Group Message Protocol. IGMP is used when one host needs to send data to many destination hosts. This is called multicasting. The addresses used to send a multicast data packet are called multicast addresses. These are reserved addresses that are not assigned to hosts in a network. An example of an application that uses IGMP packets is when a router uses multicasting to share routing tables. This is explained in Chapter 7 when routing protocols are examined.  IGMP Protocol Another application to use IGMP packets is when a hosts wants to stream data to multiple hosts. Streaming means the data are sent without waiting for any acknowledgement that the data packets were delivered. In fact, in the IGMP protocol, the source doesn’t care if the destination receives a packet. Streaming is an important application in the transfer of audio and video files over the Internet. Another feature of IGMP is the data is handed off to the application layer as it arrives. This enables to begin processing the data for playback.  The Network Interface Layer The Network Interface Layer of the TCP/IP model defines how the host connects to the network. The host could be a computer connected to an Ethernet or Token- Ring network or a router connected to a frame-relay wide area network. TCP/IP is not dependent on a specific networking technology therefore, TCP/IP can be adapted to run on newer networking technologies such as ATM (Asynchronous Transfer Mode).  Section 6-2 Key Terms Well-known ports ICANN Transport Layer Protocols TCP Connection Oriented Protocol SYN SYN + ACK ACK  Section 6-2 Key Terms UDP Internet Layer IP (internet protocol) ARP IGMP Multicasting Multicast Address Network Interface Layer Chapter 6-4 IPv4 Addressing The IPv4 classes and address range The structure of the 32-bit IPv4 address Decimal 10 10 20 1 Binary 00001010 00001010 00010100 00000001 Fig. 6-12 The structure of the 32-bit IP address. The octets making up the network and host portions of the IPv4 address for classes A, B, and C. Table 6-8 The breakdown of the network and host bits by class. Class Network Bits Host Bits A 8 24 B 16 16 C 24 8 Address ranges in class A,B, and C have been set aside for private use. These addresses, called private addresses, are not used for Internet data traffic but are intended to be used specifically on internal networks called Intranets. Functionally, private addresses work the same as public addresses except private addresses are not routed on the Internet. These are called non-routable IP address and are block by the Internet Service Providers.  ARIN IP addresses are assigned by ARIN, the American Registry for Internet Numbers. www.arin.net ARIN assigns IP address space to Internet Service Provides (ISP) and end users. ARIN only assigns IP address space to ISPs and end users if they qualify. This requires that the ISP or end user be large enough to merit a block of addresses. In the case where blocks of addresses are allocated by ARIN to the ISPs, the ISPs issue addresses to their customers. For example, a Telco could be the ISP that has a large block of IP addresses and issues an IP address to a user. A local ISP could also be assigned a block of IP addresses from ARIN, but the local ISP must have a large number of users.  ARIN ARIN also assigns end users IP addresses. Once again, the end user must qualify to receive a block of addresses from ARIN. This usually means that the end user must be large. For example, many universities and large businesses can receive a block of IP addresses from ARIN. However, most end users will get their IP addresses from an ISP (e.g. Telco) or have IP addresses assigned dynamically when they connect to the ISP.  Section 6-4 Key Terms IPv4 Class A, B, C, D, and E Non-routable IP Addresses ARIN Chapter 6-5 Subnet Masks  Subnetting Subnetting is a technique used to break down (or partition) networks into subnets. The subnets are created through the use of subnet masks. The subnet mask identifies what bits in the IP address are to be used to represent the network/subnet portion of an IP address. The subnets are created by borrowing bits from the host portion of the IP address as shown. The network portion of the IP address and the new subnet bits are used to define the new subnet. Routers use this information to properly forward data packets to the proper subnet. The Class C network, shown is partitioned into four subnets. It takes 2 bits to provide four possible subnets therefore 2- bits are borrowed from the host bits. This means the process of creating the four subnets reduces the number of bits available for host IP addresses. The equations for calculating the number of subnets created and the number of hosts/subnet.  192.168.12.0 Network Subnet A Subnet B Subnet C Subnet D subnet mask = ? Partitioning a network into subnets.  Network Host 24 + 2 = 26 bits 6 bits The next step is to determine the subnet mask required for creating the four subnets. Recall that creating the four subnets required borrowing 2 host bits. The two MSB (most significant bit) positions, borrowed from the host and network portion of the IP address must be included in the subnet mask selection. The purpose of the subnet mask is to specify the bit positions used to identify the network and subnet bits. Applying equations 6-1 and 6-2 to calculate the number of subnets and hosts/subnet.  192 168 12 ---- Creating the subnet mask to select the 192.168.12.0 subnet.  Network + Subnet subnet Network Host Network Network Subnet bits Host bits Borrowed bits Borrowing bits from the host to create subnets. Example 6-8 Given a network address of 10.0.0.0, divide the network into 8 subnets. Specify the subnet mask, the broadcast addresses, and the number of usable hosts/subnet. Network + Subnet bits host bits 8 + 3 5 + 8 + 8 Example 6-9 Determine the subnet mask needed for the router link shown. Only two host addresses are required for this router-to-router link. Example 6-9 Determine the subnet mask needed for the router link shown. Only two host addresses are required for this router-to-router link. Answer: 255.255.255.252  Subnet Mask Computer’s use the subnet mask to control data flow within network’s. The subnet mask is used to determine if the destination IP address is intended for a host in the same LAN or if the data packet should be sent to the gateway IP address of the LAN. The gateway IP address is typically the physical network interface on a layer 3 switch or a router.  Subnet Mask For example, assume that the IP address of the computer in the LAN is 172.16.35.3. A subnet mask of 255.255.255.0 is being used. This means that that all data packets with an IP address between 172.16.35.0 and 172.16.35.255 stay in the LAN. A data packet with a destination IP address of 172.16.34.15 is sent to the LAN gateway. The 255.255.255.0 subnet mask indicates that all bits in the first three octets must match each other to stay in this LAN.  Destination Network ? This can be verified by “ANDing” the subnet mask with the destination address as shown. 172. 16. 35.3 255.255.255.0 172. 16. 35.0 in the same subnet as the LAN 172. 16. 34.15 255.255.255.0 172. 16. 34. 0 not in the same subnet as the LAN  Summary This section has demonstrated techniques for establishing subnets and subnet masks in computer networks. Examples have been presented that guide the reader through the process of borrowing bits to determining the number of available hosts in the subnet.  Section 6-5 Key Terms Subnet Mask