Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Wake-on-LAN wikipedia , lookup
Computer network wikipedia , lookup
Registered jack wikipedia , lookup
Piggybacking (Internet access) wikipedia , lookup
List of wireless community networks by region wikipedia , lookup
Cracking of wireless networks wikipedia , lookup
Zero-configuration networking wikipedia , lookup
Airborne Networking wikipedia , lookup
Lesson 5: Other Network Architectures At a Glance This lesson covers the basic characteristics of Token Ring, FDDI, ARCNet and LocalTalk architecture. What You Will Learn After completing this lesson, you will be able to: D Describe the characteristics of Token Ring architecture. Describe the characteristics of FDDI architecture. Describe the characteristics of ARCNet architecture. Describe the characteristics of LocalTalk architecture. Design a Token Ring network Select appropriate network architecture when given a set of specifications. Draft 1 Other Network Architectures Unit 2 Student Notes Tech Talk 2 Active Monitor – The computer device on a Token Ring network whose responsibility is to ensure that the network is functioning properly. ARCNet – A Token Ring network that runs over tine twisted pair RJ62/U cable at speeds of either 2.5 or 4 Mbs. Beacon Frame – A specialized frame, or signal, used in both Token Ring and FDDI networks. Beacon frames are used to indicate network malfunctions, such as a break in the ring. Claim Frame – A specialized frame, or signal, used in both Token Ring and FDDI networks that indicates that a new computer device on the ring has been designated the active monitor. Fiber Distributed Data Interface (FDDI) Architecture – A high speed, dual token passing access network that uses fiber optic cable. Medium Interface Connector (MIC). 1. An IBM designed connector, used for Type 1 and Type 2 cabling, that may be connected to another like connector. Two connectors are attached simply by flipping one of them over. 2. An interface used in FDDI networks, to connect fiber optical cable to a computer device or another fiber optical cable segment. The MIC is also used to terminate fiber optical cable. Ring Wrap – The joining of the primary and secondary FDDI rings in the even of a break in the primary ring. This process allows the network to heal itself and continue to operate. Timed Token Frame – Specialized data packet used in FDDI networks that gives permission to a computer device to transmit data. The rotation time around the ring is timed making it possible to determine when a device should have token access. Token Frame – Specialized data packet used in Token Ring networks to give permission to computer devices to transmit data. Token Ring Architecture – An IBM, IEEE 802.5 physical star, logical ring topology technology that uses a token passing access method for transmitting data. DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures Token Ring Architecture Token Ring architecture, introduced in the mid 80s by IBM and defined by the IEEE 802.5 standard, is a physical star, logical ring topology. In Token Ring networks, computer devices are connected logically in a ring with each device connected separately to a specialized Token Ring hub called a multistation access unit (MSAU or MAU). The function of this hub is to ensure that the packets of data are transmitted around the ring and has the ability to bypass a device in case of failure on one of the ports. Token Ring Multistation Access Unit (MAU) Traditional Token Ring networks transmit signals at a speed of either 4 or 16 Mbs using a token that is passed from computer to computer around a network. [Recent Token Ring technology with speeds of 100 and 128 Mbs is called fast Token Ring networks. These networks operate like traditional Token Ring networks]. In order to send data, a computer device must capture the token. The token, which is continuously transmitted around the ring, is a 24-bit frame with three fields, a Start Delimiter (SD), an Access Control (AC), and an Ending Delimiter (ED). Token Frame Format SD AC ED The access field carries a signal, either a 0 or 1, that tells the computer device whether or not it is available to carry data. If available, the access control signal is a 0, and the computer device captures the token frame, inserts the information being transmitted in between the access field and the ending delimiter, and then sends the entire frame. When workstation A transmits to workstation C, workstation A grabs a free token and changes the AC to a 1 indicating that the token is no longer available for use and encapsulates its data within the token frame DRAFT 3 Other Network Architectures Unit 2 Workstation A Captures the Free Token D Free Token A C B The token with its encapsulated data travels around the network from one computer to the next, where each device accepts the frame and checks the destination address. If the hardware addresses match, the device processes the data, if it does not match the data is retransmitted to the next device until the token reaches its intended destination. 4 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures Data Encapsulated in Token Frame D A C Data B The destination device accepts the frame and copies the data, verifies receipt, and returns the token frame to the network where it continues around the ring until it reaches the original sending device. The sending device recaptures the token that contains information that the frame was received and also contains error control information. After stripping the original data from the frame, the sending device returns the available token to the network and the process continues. DRAFT 5 Other Network Architectures Unit 2 Workstation C Accepts Data and Sends to Back to A to be Stripped D Data Data A C Token B Four Mbs Token Rings only allow one token on the ring at a time, sixteen Mbs Token Rings allow multiple data frames to be on the ring at the same time. Token Ring networks are not as susceptible to signal degradation as other network types, since each device acts like a repeater, regenerating the signal before transmitting it to the next device. Token Ring networks fail more gracefully than Ethernet networks when they are overloaded. Since they are so reliable, diagnostic and troubleshooting measures are often built into the hardware. Also, priority can be assigned in Token Ring networks. Although they work quite well, Token Ring networks are currently being phased out for several reasons. They have very complicated protocols, which makes them both difficult to troubleshoot and more expensive than other technology. Token Ring is basically IBM, so there are compatibility issues with equipment from other manufacturers who also are not as interested in new Token Ring technology since the market isn’t as profitable as the Ethernet market. Additionally, 4 Mbs networks are too slow. 6 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures Token Ring Frame Format Token Ring frame format begins with the 8 bit Start Delimiter followed by the 8 bit Access Control. The next field, is a Frame Control field, which indicates whether the frame contains Media Access Control information for all network devices or only data for only a single destination device. This field is followed by the Destination Address field (either 16 or 48 bits), the Source Address field (either 16 or 48 bits), the Data field (has no determined size), the Frame Check Sequence field (32bits), the End Delimiter field (8 bits), and finally the 8bit Frame Status field. Token Ring Frame Format SD AC Frame Control Destination Address Source Address Data Field FCS ED 8 bits 8 bits 8 bits 16 or 48 bits 16 or 48 bits >0 bits 32 bits 8 bits Detecting Errors through Beaconing One computer device on a Token Ring network, usually the first device recognized when the LAN comes up, is designated the active monitor. It is the responsibility of the active monitor to ensure that the network is functioning properly. Every seven seconds the active monitor station sends a signal, called a beacon, which checks for malfunctioning devices and problems such as errors in delivery of frames. Each successive device on the ring receives and forwards the beacon signal. If a device does not receive the beacon announcement, it sends a message on to the network indicating that there is a malfunction, and the Token Ring tries to selfcorrect the problem. If the active monitor malfunctions, its nearest active upstream neighbor (NAUN) becomes the new active monitor and sends out a Claim Token notifying all other devices of the change in active monitor status. DRAFT 7 Other Network Architectures Unit 2 Token Ring Components Cabling The specified cable in the IEEE 802.5 Token Ring standard is 150 ohm STP. IBM Token Ring networks use UTP, STP, and fiber optic cable types. The chart below indicates the IBM cable types, their description, and common uses. IBM Cable Type Description Type 1 Two-pair 22 AWG STP wire used for conduits and outside walls Type 2 Two-pair 22 AWG STP wire for data and fourpair 26 AWG wire, outside the shield, used for telephone (voice). Commonly used for trunk cable. Type 3 Four-pair 22 or 24 AWG UTP wire, which requires a media filter for use in Token Ring networks. Susceptible to EMI since it is unshielded wire. Also can’t be used for 16 Mbs Token Ring networks. Type 5 100/140 micron two strand fiber optic cable, which is used for the main ring of Token Ring networks. Type 6 26 AWG flexible STP wire used for patch or extension cables. Type 8 Single copper core 26 AWG STP specifically designed for use under carpets. Type 9 Single pair Plenum grade 26 AWG STP fire resistant wire. Used in walls and ceilings. Token Ring Network Interface Adapter Cards Token Ring Network Adapter Cards, the specialized interface used to connect devices on Token Ring networks are available for both 4Mbs and 16Mbs Token Ring networks. A 16 Mbs Token Ring NIC can be used on a 4 Mbs network; however a 16 Mbs network must use 16 Mbs adapter cards. 8 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures Multistation Access Units Multistation Access Units (MAU or SMAU), are specialized hubs (sometimes called concentrators) made specifically for Token Ring networks. These hubs have an internal wiring arrangement that allows the computers to be connected in a continuous ring. MAUs have the ability to bypass failed computer devices connected to the ring. Typical MAUs connect eight or more computer devices and, according to standards, up to 12 MAUs can be interconnected. Adapter and Patch Cables A Token Ring adapter cable typically has a nine-pin connector at one end that attaches to the back of the NIC. and a special IBM data connector that connects to the MAU at the other end. Adapter cables may also have telephone-jack-type cable connectors. Patch cables are Type 6 IBM cables that come in standard lengths of 8, 30, 75, or 150 feet. They are used to extend the distance of a computer device from the MAU, or to attach two MAUs. Media Filters A media filter is used to connect a Token Ring adapter card to an RJ-11 or RJ-45 wall jack. A media filter is required when Type 3 telephone cable is used or when a NIC card with a DB-9 interface to connected to hub. The media filter converts different signals and reduces noise interference. Connectors Many different types of connectors are supported within a Token Ring network. The type of connector specifies the type of cabling that is acceptable. If UTP cabling is used, both the cable and connectors must have the same category rating. Token Ring connectors include the following: DB-9 Connector. Used for STP cable. May be used for trunk a connection or device inaction. Most commonly found on the back of a Token Ring NIC card. A DB-9 must have a media filter attached if used with UTP cable. DRAFT 9 Other Network Architectures Unit 2 DB-9 and IBM Data Connector DB-9 Connector NIC STP Cable IBM Data Connector Medium Interface Connector (MIC). An IBM designed connector, used for Type 1 and Type 2 cabling. A MIC may be attached to another like connector simply by flipping one of them over. IBM Data Connector 10 RJ-45. An 8-pin standard telephone-jack-type connection used to connect UTP or STP cables. RJ-11. A 4-pin telephone-jack connector used for Type 3 cable connections. DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures Straight Tip (ST). Connector used with fiber cable . Two connectors are required per port, one transmits and one receives. Straight Tip Connector Check Your Understanding What are the advantages of a Token Ring Network? What is a token? What is a MAU? Fiber Distributed Data Interface (FDDI) Fiber Distributed Data Interface (FDDI) is a high speed (100 Mbs), fiber optic LAN technology that uses the token passing method to access the network. The American National Standards Institute (ANSI) developed standards for FDDI networks (X3T9.5) that address the Physical and Media Access (sub)layers of the OSI model. It assumes the use of IEEE 802.2 Logical Link Control sublayer standard above the MAC layer. FDDI uses physical star, logical ring topology. Unlike Token Ring, which has only one ring, FDDI is a dual ring topology. FDDI is commonly used between LANs in metropolitan area networks to provide high speed connections. Like Token Ring, FDDI uses a token frame to pass data from one station to the next around a ring until it returns to the source device; however, an additional clocking field is added to the beginning of the token. This field is added because FDDI transmissions may be synchronous and require a clocking mechanism. Voice and video transmissions are examples of data that require synchronization. DRAFT 11 Other Network Architectures Unit 2 When a free token is available, a computer device is allowed to transmit its data. Unlike Token Ring, which can transmit only one frame at a time, with FDDI the computer device can transmit as many frames as possible until a predefined time limit is reached. When the device either has no more frames to send or the time limit is reached, it stops transmitting data and immediately releases an available token. In Token Ring, the free token was not released until after the sending device received the frame it sent indicating receipt and/or errors. Because the token is transmitted as soon as a computer device is finished transmitting frames, it is possible for a device on the ring to transmit new frames while other frames are still circulating around the ring. It is therefore possible for multiple frames from multiple devices to be on the network simultaneously. FDDI networks are commonly used to connect LANs where either EMI or distance is problems. Computer devices can be as far apart as 2 kilometers and FDDI networks can support up to 1000 devices per LAN. 12 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures FDDI Rings FDDI is able to send more than one frame at a time because it uses dual, rings with data moving in opposite directions on each ring, as shown in the illustration below. This also allows more than one computer to transmit at the same time. FDDI Dual Rings Primary ring Secondary ring The dual rings are classified as primary or secondary. Devices on FDDI networks may be connected to both primary and secondary rings or only the primary ring. If there is a malfunction on the primary ring, the secondary ring automatically wraps to the first ring forming a complete ring once again. This is referred to as “ring wrap” and is an automatic function of FDDI. A type of claim token frames is used in FDDI networks to detect errors in transmission or timing. A device connected to both the primary and secondary rings is classified as a dual-attached station or Class A station. A single-attached or Class B station, is attached to only the primary ring. Typically, a Class A station would be a hub and a Class B, a computer workstation. The Class B device would connect to the primary ring and through that connects to the hub. DRAFT 13 Other Network Architectures Unit 2 FDDI Frame Format In addition to the four token fields FDDI network include the following fields: FDDI The diagram below shows the FDDI Frame Format. FDDI Frame Format LLC-PDU SSAP Address DSAP Address Frame Control Information MAC Frame Preamble Starting Frame Delimiter 8 octets 1 octet Frame Control Dest. MAC Address Source. MAC Address Information 2 or 6 octets 2 or 6 octets 0-4478 octets 1 octet Frame End Check Frame Sequence Delimiter 4 octets .5 octet Preamble: this field, which consists of all 1s, is used as a clocking mechanism and indicates the beginning of a frame. Start Delimiter: designates the physical start of the FDDI frame. ES-AV0025000 Frame 5/33 control: indicates the length of the address and the transmission type (synchronous/asynchronous and data/network information). 14 Destination Address field. Source Address field. Data: application and upper layer protocol data. CRC: error checking frame. End Delimiter: signifies the end of the data frame. Frame Status field: offers further error checking. DRAFT Internetworking Fundamentals Frame Status 1.5 octets Unit 2 Lesson 5: Other Network Architectures FDDI Media Cabling Fiber optic cable is specified as the standard for FDDI and may be single or multi-mode fiber. Single mode fiber optic cable uses laser technology and can transmit up to a maximum of 20 km without using repeaters. Multimode fiber is less expensive. Instead of laser technology, it employs LED, light emitting diode technology, and can transmit signals of to a maximum distance of 2 km. STP Type 1 and UTP Category 5 copper cable may be used for the ring device connections. Dual Attachment Concentrator (DAC) A dual attachment concentrator is a hub used in FDDI networks that are capable of attaching to dual counter rotating rings. DACs have additional ports, called trunk ports, used to connect to additional concentrators or other FDDI computer devices. FDDI Network Adapter Cards The transceiver in FDDI networks in built into the FDDI NIC. It is a laser transceiver used to convert digital data to light impulses and vice versa. This conversion allows signals to travel over both copper and fiber optic cabling thus enabling connections to PCs. It is not unusual for some types of NICs to have more than one transceiver. For example, many Ethernet NICs have more than one transceiver, but each transceiver must have its own connector type on the card. FDDI Connectors The connectors used in FDDI networks are Media Interface Connectors (MIC), Straight-tip Connectors (ST), and RJ-45 Connectors. There are several types of MICs. They are typically color coded to assist in allowing only desirable port connections. During installation and troubleshooting when cable connections are often moved, it is important to keep the color-coded key attached to the MIC connector. Occasionally fiber cabling may use a combination of connectors with a MIC at one end and a ST connector on the opposite end. DRAFT 15 Other Network Architectures Unit 2 LocalTalk Since its introduction in 1984, Apple Computer has included a built-in network interface on every Macintosh. LocalTalk is a low-speed network that was designed to work in small workgroups with a few devices. The network transmits data at 230 kilobits per second, about 40 times slower than the slowest Ethernet network. In contrast to Ethernet use of CSMA/CD, LocalTalk uses the CSMA/CA access method. LocalTalk Connector module 8-pin plug LocalTalk cable The original version of LocalTalk from Apple used a shielded 2-wire cable to transmit data. The system used a bus topology in a fashion similar to 10Base2. Although LocalTalk is easy to install and use, it is very slow and does not support more than 253 devices and is limited to a maximum of 32 devices per daisy chain. Check Your Understanding What are differences between FDDI and Token Ring networks? 16 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures LocalTalk Addressing LocalTalk provides three levels of addressing: node, network, and socket. Node ID You'll remember that one of the requirements of a Data Link layer protocol is to move data from device-to-device on a single LAN. To do so, each device on the network requires a unique address. On Ethernet and Token Ring network interface cards, this address is located in some form of nonvolatile memory. For the Macintosh, Apple chose a different approach. Instead of storing a unique network address into every Macintosh computer, an address is dynamically assigned each time the computer is turned on. Apple calls this address a Node ID. The Node ID is a Data Link layer address that uniquely identifies each device on a single network. The Node ID is 8 bits and ranges from 0 to 255. Node IDs 0, 254, and 255 are reserved resulting in a possible 253 addresses per network. Check Your Understanding Compare the speed of LocalTalk with Ethernet: How is LocalTalk addressing different from Ethernet and Token Ring? Network ID The Network ID is a Network layer address that uniquely identifies each network on an internetwork. The Network ID is 16 bits and ranges from 0 to 65,535. This allows a maximum of 65,536 networks each with 253 devices for a total of 16,580,608 devices. DIN type connectors for STP SSTP connectors generally must be soldered during installation, LocalTalk originated as STP but can now use UTP with RJ-45 connectors. The Datagram Delivery Protocol (DDP) is LocalTalk's Network layer protocol. DDP provides connectionless, best-effort data delivery and provides no acknowledgement sent to the receiver ARCNet Attached Resource Computer network was developed in the late 70s for small LANs is a token passing media access control network topology, that transmits data at speeds 2.5 Mbs. Tokens in ARCNet networks are passed according the MAC address rather than in succession from one computer to the NAUN computer device. DRAFT 17 Other Network Architectures Unit 2 Topology is either bus, star, or a combination. If bus topology is used, the maximum distance per segment is 305 meters. With the addition of an active hub that repeats the signals, the maximum distance between the computer device and the hub is 610 meters when using BNC connectors and coaxial cable and 244 meters when using twisted pair and RJ-11 or RJ-45 connectors. ARCNet Media ARCNet networks use coaxial, UTP, STP, and fiber optic cable although the standard cable is 93-ohm, RG-62A/U coaxial. 18 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures Hybrid Architectures Incorporating more than one type of architecture when connecting and expanding LANs is not uncommon. A specialized bridge, called a translating bridge, must be used when interconnecting LANs using different data link layer protocols and different physical network media (for example, Token Ring to FDDI). It must be able to convert the frame format of one media type into the frame format of another media type. Translating Bridge DRAFT 19 Other Network Architectures Unit 2 U2L5 Supplemental #1 Ethernet or Token Ring? Write a one half -page scenario for two companies that includes the following information: Type of company Number of employees Network access requirements Network reliability needs Physical layout requirements Type of equipment Type and amount of data to be transmitted Make one scenario company use an Ethernet network (so make up company characteristics to fit that architecture) and one scenario to use an IBM Token Ring network (again, make up company charactoristics to fit token ring strengths) Your two scenarios should emphasis the strength of both architectures. Don’t make guesses. From the reading what did you learn? Include in your analysis your reasons for the choice. Defend as many aspects of your choice as possible based on facts about each type. U2L5 Supplemental #2 Give the answers to the following blank spaces. Also, after each question tell where you found the answer. Some will be from the lesson reading in which case give the page number. Others will be found on the net so give the URL where you found it. 1. uses a physical star, logical ring topology with each network device connected separately to a multistation access unit. 2. This network technology designed by is a low-speed network (230 Kbps) that was designed to work in small workgroups with a few devices. 3. This network technology can use either a bus, star or combination topology and was designed in the late 70s for small LANs. The original version used token passing at 2.5Mbps. 20 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures 4. The most commonly installed Token Ring networks run at 5. . networks are not as susceptible to signal degradation as other network types since each device acts as a repeater. 6. Token Ring networks use a devices. signal to check for malfunctioning 7. The IEEE Token Ring specification is 8. A 16 Mbps Token Ring NIC . be used on a 4 Mbps Token Ring network. 9. A Token Ring hub is commonly referred to as a . 10. MAU is an acronym for _______________________________________. 11. A DB-9 connector used in a Token Ring network must have a attached for device connection if used with a UTP network. 12. According to Token Ring standards, up to ______ MAUs may be interconnected. 13. _________ can be used between LANs in metropolitan area networks to provide high speed connections. 14. A ________ FDDI device is connected to both the primary and secondary rings. 15. Multi-mode fiber optic cable can transmit to a maximum of ________ on a FDDI network without using repeaters. 16. The hub used in FDDI networks that allows attachment to the dual rings is called a . 17. LocalTalk devices use ________ addresses for network communications: 18. A ___________ is used to interconnect LANs using different data link layer protocols and different physical network media (example: Ethernet to FDDI). 19. Here is the format for a Token Frame: And here is the format for an Ethernet Frame: When compared the three most obvious differences are: DRAFT 21 Other Network Architectures Unit 2 U2L5 Supplemental #3 Other Networking Architectures Review Questions Part A 1. Token Ring networks operate at a. 10, 100 or 1000 Mbps b. 4, 16, 100 or 128 Mbps c. 1 Gbps d. 10, 16 or 1000 Mbps e. 4 or 10 Mbps 2. A device may use the token frame to send data if a. The Start Delimiter is 0 b. The End Delimiter is 1 c. The hardware addresses match d. The Access Control signal is 0 e. The Start Delimiter is 1 3. The token frame size is a. 16 bits b. 24 bits c. 32 bits d. 48 bits e. 64 bits 4. After copying data from the token frame, a receiving device a. Releases the token b. Reads error control information from the frame c. Uses the token frame to send new data d. Destroys the token frame e. Send the frame back to the sending device 5. Token Ring networks a. Fail more often than Ethernet networks 22 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures b. Fail more gracefully than Ethernet networks c. Never fail d. Cannot accept priority assignments e. Must use fiber optic cabling 6. To detect and correct errors a. Every device on a Token Ring network is an active monitor b. Each device on a Token Ring network diagnoses its own errors c. Each device gives control to its nearest active upstream neighbor d. One device is designated as the active monitor e. All devices send out a Claim Token 7. An MAU a. Connects Token Ring devices into a ring b. Turn off the ring when any connected device fails c. Route power to connected devices d. Switch traffic to neighboring networks e. Cannot connect to other MAUs Part B 1. FDDI operates at a. 10 Mbps b. 4 or 16 Mbps c. 100 Mbps d. 1000 Mbps e. 4.5 Mbps 2. To transport streaming media data, FDDI a. Opens a switched circuit b. Can synchronize data with a clocking field c. Can only transmit one frame when the token has been captured d. Uses fiber optic cabling 3. When an FDDI sending device has captured a token a. It can only transmit one frame DRAFT 23 Other Network Architectures Unit 2 b. It can transmit as many frames as it wants c. It can only transmit error diagnostics d. It can transmit frames until a time limit expires e. It releases the token 4. A secondary ring in FDDI a. Automatically steps in if the primary ring fails b. Allows priority communication to select devices c. Doubles communication speed d. Connects to Token Ring networks Part C 1. Which computer manufacturer uses local talk? a. IBM b. Digital Equipment Corporation c. Intel Corporation d. Motorola e. Apple Computer 2. AppleTalk operates at a. 230 Kbps b. 1 Mbps c. 10 Mbps d. 100 Mbps e. 1 Gbps 3. AppleTalk Node Id’s are assigned a. By the manufacturer b. By the user c. By the computer when the device is powered up d. By the computer when the device is installed e. By the server 4. AppleTalk connects using a. Fiber optic cable 24 DRAFT Internetworking Fundamentals Unit 2 Lesson 5: Other Network Architectures b. Coaxial cable c. Twisted pair cable d. Microwave radio e. Photonic switches Part D 1. ARCNet operates at a. 230 Kbps b. 1 Mbps c. 2.5 Mbps d. 10 Mbps e. 1 Gbps 2. ARCNet tokens are passed by a. nearest active upstream neighbor b. nearest active downstream neighbor c. Random walk d. MAC address e. NAUN computer device 3. ARCNet connects using a. Twisted pair or coaxial cable b. Fiber optic cable c. Infrared light d. Microwave radio DRAFT 25