Campus Network Design - PDF Free Download

Content Ethernet Standard Transparent Bridges LAN Switches LAN and Switch Operation Loop Resolution Virtual LANs, InterVLAN Routing Router Redundancy Switch Security Campus Network Design 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-2

MAC techniques Contention Medium is free for all A node senses the free medium and occupies it Example: Ethernet, IEEE 802.3 Round robin Give every body a turn Inefficient for lightly loaded network Example: Token Ring/IEEE 802.5, Token Bus/IEEE 802.4, FDDI Reservation schedule a time slot like TDM Example: DQDB 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-7

Ethernet and IEEE 802.3 1973: First LAN Ethernet 2.94 Mbps (developed by Xerox Palo Alto Research Center, including Bob Metcalfe (who later founded 3Com)) 1980: 10Mbps ethernet specification by DEC, Intel, and Xerox 1985: becomes IEEE 802.3 standard (already widely used before this time) 1995: 100Mbps Fast Ethernet standardized in IEEE 802.3u (already widely used before this time) 1998: 1Gbps Gigabit Ethernet IEEE standard issued 1999: 10Gbps ethernet under development 2002: 10GbE Standard issued 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-8

Medium Access Control Logical Link Control (LLC) provides single data link control protocol for all IEEE LANs while Media Access Control (MAC) provides different protocols for different LANs. MAC contains synchronization, flag, flow and error control specifications necessary to move information from one place to another and the physical address of the next station to reduce and route a packet. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-11

Medium Access Control The role of Data Link layer is to permit the transfer of data between the stations and detect transmission errors. IEEE divides this layer into separated sub-layers : MAC (Medium Access Control) and LLC (Logical Link Layer) The MAC sublayer control the access of medium using access method. The LLC provides interface to next upper layer. The data link layer protocol performs: perform functions related to medium access (MAC sublayer) concerned with the transmission of a link-level between two nodes (LLC sublayer) Network Data Link Physical LLC MAC Logical Link Control sublayer Medium Access Control sublayer 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-12

Ethernet Xerox (Bob Metcalfe) performed initial development of Ethernet in 1976 (2.94 Mbps,over 100 personal workstations,1-km long cable) and was later joined by the Digital Equipment Corporation (DEC) and Intel to define the Ethernet 1 specification in 1980. The same group subsequently released the Ethernet 2 specification in 1984. The Ethernet specification describes a packet switching CSMA/CD LAN. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-13

10Base5 tap : cable does not need to be cut transceiver : send/receive, collision detection, electronics isolation AUI : Attachment Unit Interface Use for backbone networks maximum segment length=500m maximum number of stations per segment=100 0.5 Coax vampire tap BNC connector transceiver AUI cable minimum distance between two stations = 2.5 m maximum network distance between two stations = 2.5km NIC 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-21

10Base2 BNC connector No drop cable use for office LAN What is its benefit since length < 500m? 0.25 Coax BNC T-connector NIC maximum segment length=185m maximum number of stations per segment=30 minimum distance between two stations = 0.5 m maximum network distance between two stations = 925 m 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-25

Group Discussion ให อภ ปรายความแตกต างของ 10 Base5 และ 10 Base2 ให ว เคราะห ว าในการใช งานจร ง ร ปแบบเคร อข ายแบบ 10 Base5 และ 10 Base2 น าจะเก ดป ญหาอะไรได บ อย 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-26

StarLAN Developed by by Tim Rock and Bill Aranguren at AT&T Information Systems as an experimental system in 1983. Used a star topology from a central hub. The standard known as 1BASE5 was adopted as 802.3e in 1986 The original StarLAN ran at a speed of 1 Mbit/s. A major design goal in StarLAN was reduction in Ethernet installation costs by the reuse of existing telephone onpremises wiring and compatibility with analog and digital telephone signals in the same cable bundle. Used UTP (Unshielded Twisted Pair) Cat.3 1987, Synoptics introduce LATTISNET and delivered 10 MBps over telephone wire, also known 10 Base T 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-27

10Base-T A hub functions as a repeater UTP category 5 uses 2 pairs of wires terminated by an eight-bin (RJ-45 style) connector. This means that 4 pins of the 8-pin are used. The transmit and receive data signal on each pair of the segment are polarised, with one wire of the signal pair carrying the positive (+) signal and the other carrying the negative (-). Pin 1 2 3 4 5 6 7 8 Sig TD+ TD- RD+ U U RD- U U hub Medium Dependent Interface (MDI), RJ45 maximum segment length = 100m NIC 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-32

IEEE 802.5 (Token Ring): Ring Topology Shared ring medium: all nodes see all frames Round Robin MAC Protocol: determines which station can transmit A special 3 byte pattern, the token, circulates around the ring perpetually and represents the "right to transmit" This establishes round robin media access Data flow is unidirectional All data flows in a particular direction around the ring; nodes receive frames from their upstream neighbor and forward them to their downstream neighbor Data rate: 4 or 16 Mbps 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-34

IEEE 802.5 (Token Ring) using a Hub The star wired ring topology uses the physical layout of a star in conjunction with the token passing data transmission method. Data are sent around the star in a circular pattern. This hybrid topology benefits from the fault tolerance of the star topology and the reliability of token passing. 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-39

LAN characteristics confined within geographical area relatively high data rate under single management LAN Ingredients... Topology bus, star, ring Transmission medium twisted pair, coaxial, fiber optics, wireless Medium access techniques protocol to coordinate the sharing of media hub hub hub router hub stations stations stations server 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-41

Topology Topology defines how nodes/stations are connected (structure of logical layout) 3 main LAN typical topology : bus/tree : all nodes connected to a common medium star : all nodes are joined to a central nodes ring : nodes form a ring by point-to-point links to adjacent neighbors bus star ring 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-42

Topology : Bus A B C D D B and C Application Presentation Session Transport Network Data Link Physical D Application Presentation Session Transport Network Data Link Physical 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-43

Topology : Ring A A A node functions as a repeater C A B C A B only destination copies frame to it, all other nodes have to discarded the frame B transmits frame addressed to A C ignores frame Unidirectional link A A C A B C A B A copies frame C absorbs returning frame 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-44

Topology : Star Each station attaches to the central node Two point-to-point links for transmitting and receiving Two alternatives operation: broadcasting and switching Easy to manage with relative low cost. But very vulnerable, since it depends entirely upon the operation of the central node. A A B C A A shared hub broadcasts packet to every ports but only destination copies frame A B C C transmits frame addressed to A A B C A switch hub retransmits packet to the destination only 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-45

Overview of LAN Standard 802.2 802.3 802.4 802.5 Logical Link Control CSMA/CD (Ethernet) Token Bus (Bus topology with logical ring) Token Ring (it followed Ethernet and is now widely used in the large number of IBM networks) 802.6 Distributed Queue Dual BUS --MAN standard FDDI Fiber Distributed Data Interface (also using token) 802.2 LLC 802.3 CSMA/CD 802.4 Token Bus 802.5 Token Ring 802.6 DQDB FDDI 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-46

IEEE 802.3 Specification Various standard defined for IEEE802.3 with a concise notation: 10Base5 -- thickwire coaxial, 500m 10Base2 -- thinwire coaxial or cheapernet, 185m 10BaseT -- twisted pair (most widely used today, 100m) 10BaseF -- fiber optics 10Broad36 -- broadband (only 802.3 standard 1/2 coax, 1800m) Fast Ethernet 100BaseTX, 100BaseT4, 100BaseFX, 100VG-AnyLAN(802.12) GigaEthernet 1000 Mbps (802.3z) available on fiber and on coax, UTP IsoEthernet (Category 3, 10Mbps Ethernet and 6.144Mb 96 channels ISDN) 10 Base 5 data rate in Mbps signaling baseband or broadband maximum segment length in hundreds of meters 2003, Cisco Systems, Inc. All rights reserved. BCMSN v2.0 1-47