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Chapter 7. Non-Ethernet Network ( Token Ring and FDDI ). Ethernet is the Most Popular Networking Technology. Token Ring. IEEE 802.5 Logical topology: Ring topology Physical topology: Star topology ( Star-Ring Topology) Token Ring hub = MAU = MSAU. Token Ring. Token Ring frame
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Chapter 7 Non-Ethernet Network (Token Ring and FDDI)
Token Ring • IEEE 802.5 • Logical topology: • Ring topology • Physical topology: • Star topology (Star-Ring Topology) • Token Ring hub = MAU = MSAU
Token Ring • Token Ring frame • Five major parts of a Token Ring frame: • Source/Sender MAC address • Destination MAC address • Data from Layer 3: Packet • Frame Check Sequence • Token
Token Ring • Token Ring frame travels in ONE direction • Upstream neighbor: • The computer from which a computer receives the Token Ring frame • Downstream neighbor: • The computer to which a computer passes the Token Ring frame
How does Token Ring work? • FREE TOKEN (i.e., a frame that contains the Token only, WITHOUT Source MAC address, Destination MAC address, Data from Layer 3, Frame Check Sequence) circulates in the network • After receiving a free Token, the computer creates the Token Ring frame and passes it to its downstream neighbor • The frame will be passed from one computer to another • Every computer will compare the Destination MAC address in the frame to its own MAC address. If they do not match, it passes the frame to its downstream neighbor. If they match, it decapsulates the frame to process the information further • After decapsulating the frame, it then creates a new frame addressed to the Sender containing message confirming that the frame has been received properly (without any error) (Acknowledgement frame) • The new frame will be passed from one computer to another until it reaches the Sender • The Sender then removes all information from the frame but the Token and releases the free token back to the network
How does Token Ring Work? • Please visit the following Web pages: http://www2.rad.com/networks/1997/nettut/token_ring.html http://www.netbook.cs.purdue.edu/anmtions/anim06_3.htm http://www.datacottage.com/nch/troperation.htm
Token Ring • Token Passing: • The method of passing the frame to all computers in a network in a round-robin fashion by using a token • The network access method that uses a token to determine which computer has access to the network at a given moment
Token Ring • There are two types of Token Ring network technology: • Token Ring over STP • Twopairs of STP cable • An MAU can support up to 260nodes • The STP cable connecting an MAU with a node can be up to 100meters • The STP cable uses IBM Type-1 connectors (also known as IBM-type Data Connectors (IDC) or Universal Data Connector (UDC)) • Token Ring over UTP • Twopairs of UTP cable • An MAU can support up to 72nodes • The UTP cable connecting an MAU with a node can be up to 45meters • The UTP cable uses RJ-45connectors • Preferred because UTP is cheaper than STP
Token Ring • Connecting MAUs: • Every MAU has two special ports: Ring In (R/I) and Ring Out (R/O). • To connect two MAUs, R/I must be connected to R/O, and R/O must be connected to R/I to form a single ring among the MAUs
Token Ring versus Ethernet • No collision can occur in Token Ring • More consistent throughput/data transmission speed • Ethernet devices are cheaper • Ethernet devices uses simpler technology (Ring Topology = Active Topology = every Token Ring NIC participates actively in passing information from one computer to another; Ethernet NIC does not participate actively in passing information from one computer to another) • Ethernet devices are sold more because of the popularity of the Ethernet, and hence, more cost effective (economic of scale)
FDDI (Fiber Distributed Data Interface) • To build a MAN or WAN • Physical topology: DUAL (Two) Ring topology • The ring cable is Fiber-Optic cable • Logical topology: Ring topology • Normal condition: each ring carries a free token (two tokens available) • “Bad” condition: the two rings are wrapped to become a single ring (one token available) • Using Token-Passing method • The data transmission speed 100-200 Mbps • Maximum length of a ring: 100-200 kilometers • Maximum distance between 2 adjacent computers: 2 kilometers
FDDI (Fiber Distributed Data Interface) • If the ring cable or a workstation fails, the FDDI (the FDDI NICs) will automatically “wrap the dual rings to become a single ring” (ring wrapping). Data continues to be transmitted on the FDDI ring without performance impact during the wrap condition.
Self-Healing Mechanism Check: http://dictionary.zdnet.com/definition/FDDI.html
FDDI • FDDI uses fiber optic cable • CDDI (Copper Distributed Data Interface) was developed based on FDDI • CDDI uses CAT 5 or higher UTP with RJ-45 connectors
FDDI • http://www.cisco.com/en/US/docs/internetworking/technology/handbook/FDDI.html • What is concentrator? • Why do we need concentrator? Why don’t we connect the computers directly to the FDDI ring?
Backbone Technology • Network technology widely used to build BACKBONE network (i.e., a network connecting other networks) • Fast Ethernet • Gigabit Ethernet • FDDI
Backbone Technology • Fast Ethernet, Gigabit Ethernet
Backbone Technology • FDDI
Backbone Technology • Comparison: • Fast and Gigabit Ethernet • 100 Mbps and 1000 Mbps • Low cost • Seamless connectivity with the Ethernet LAN • FDDI • 100 Mbps (200 Mbps under normal condition) • Dual-ring topology provides high degree of fault tolerance (mission critical network) • Token-passing provides more consistent performance (no collision → no delay without of collision)