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Transcript
Network Management Chapter 1 Networking Components COMP4690, by Dr Xiaowen Chu, HKBU 1 Outline Data Communications Networking OSI Reference Model TCP/IP Protocol Architecture Networking Components More detailed contents are covered by COMP4510: Foundations of Information Technology COMP4690, by Dr Xiaowen Chu, HKBU 2 Data Communications Data communications deals with the transmission of signals in a reliable and efficient manner. Topics covered include signal transmission, transmission media, signal encoding, interfacing, data link control, and multiplexing. COMP4690, by Dr Xiaowen Chu, HKBU 3 A Communications Model Purpose of Communications Exchange of data (information) between entities Key elements • Source − • Transmitter − • Carries data Receiver − • Converts data into transmittable signals Transmission System − • Generates data to be transmitted Converts received signal into data Destination − Takes incoming data COMP4690, by Dr Xiaowen Chu, HKBU 4 A Communications Model COMP4690, by Dr Xiaowen Chu, HKBU 5 Networking Point to point communication is not usually practical Devices are too far apart Large set of devices would need impractical number of connections Solution is a communications network Local Area Network (LAN) Metropolitan Area Network (MAN) Wide Area Network (WAN) COMP4690, by Dr Xiaowen Chu, HKBU 6 Local Area Networks Smaller scope Usually owned by same organization as attached devices Data rates are high Ethernet dominates the market Office, Building, Campus Ethernet vs. Token Ring Ethernet vs. ATM Wireless LAN is now very popular COMP4690, by Dr Xiaowen Chu, HKBU 7 Metropolitan Area Networks Large area Middle ground between LAN and WAN Private or public network High speed COMP4690, by Dr Xiaowen Chu, HKBU 8 Wide Area Networks Cover a large geographical area Consists of a set of interconnected switching nodes Alternative technologies Circuit switching Telephone network Packet switching X.25 Frame relay Asynchronous Transfer Mode (ATM) Internet COMP4690, by Dr Xiaowen Chu, HKBU 9 Digital Network Five Important Components Transmission (electrical, optical, wireless) Routing and Switching Circuit switching (telephone network) Packet switching Virtual-circuit (X.25, Frame Relay, ATM) Datagram (Internet) Signaling Access xDSL, Cable Modem, WiFi/WiMax, LAN Network Management COMP4690, by Dr Xiaowen Chu, HKBU 10 Digital Network COMP4690, by Dr Xiaowen Chu, HKBU 11 Protocol Architecture A protocol architecture is the layered structure of hardware and software that supports the exchange of data between systems and supports distributed applications, such as electronic mail and file transfer. At each layer of a protocol architecture, one or more common protocols are implemented in communicating systems. Each protocol provides a set of rules for the exchange of data between systems. COMP4690, by Dr Xiaowen Chu, HKBU 12 OSI Reference Model OSI: Open System Interconnection A 7-layer model Each layer performs a subset of the required communication functions Each layer relies on the next lower layer to perform more primitive functions Each layer provides services to the next higher layer Changes in one layer should not require changes in other layers COMP4690, by Dr Xiaowen Chu, HKBU 13 OSI Reference Model Application: supporting network applications - FTP, SMTP, HTTP, etc. Presentation: handle different data representations (e.g., encryption) Session: connections between apps Transport: host-host - TCP, UDP Network: routing of datagrams from source to dest - IP, routing protocols Link: data transfer between adjacent network elements - PPP, Ethernet Physical: bits “on the wire” COMP4690, by Dr Xiaowen Chu, HKBU Application (7) Presentation (6) Session (5) Transport (4) Network (3) Data link (2) Physical (1) 14 OSI Layers Physical Physical interface between devices Mechanical Electrical Functional Procedural Data Link Means of activating, maintaining and deactivating a reliable link Error detection and control Higher layers may assume error free transmission COMP4690, by Dr Xiaowen Chu, HKBU 15 OSI Layers Network Transport of information Higher layers do not need to know about underlying technology Not needed on direct links Transport Exchange of data between end systems Error free In sequence No losses No duplicates Quality of service COMP4690, by Dr Xiaowen Chu, HKBU 16 OSI Layers Session Presentation Control of dialogues between applications Dialogue discipline Grouping Recovery Data formats and coding Data compression Encryption Application Means for applications to access OSI environment COMP4690, by Dr Xiaowen Chu, HKBU 17 TCP/IP Protocol Architecture Developed by the US Defense Advanced Research Project Agency (DARPA) for its packet switched network (ARPANET) Used by the global Internet No official model but a working one. Application layer Transport layer Internet layer (or Network Layer) Network access layer (or Link Layer) Physical layer COMP4690, by Dr Xiaowen Chu, HKBU 18 TCP/IP Protocol Architecture COMP4690, by Dr Xiaowen Chu, HKBU 19 Physical Layer Physical interface between data transmission device (e.g. computer) and transmission medium or network Characteristics of transmission medium Signal levels Data rates etc. COMP4690, by Dr Xiaowen Chu, HKBU 20 Network Access Layer Exchange of data between end system and network Destination address provision Invoking services like priority COMP4690, by Dr Xiaowen Chu, HKBU 21 Internet Layer Systems may be attached to different networks Routing functions across multiple networks Implemented in end systems and routers COMP4690, by Dr Xiaowen Chu, HKBU 22 Transport Layer Usually there is a requirement of reliable delivery of data: Error-free (Packets could be lost in the network!) Ordering of delivery TCP is mainly designed for this purpose. Another transport layer protocol in TCP/IP protocol architecture is UDP. COMP4690, by Dr Xiaowen Chu, HKBU 23 Application Layer Support for user applications e.g. FTP, TELNET, SMTP, HTTP, SNMP COMP4690, by Dr Xiaowen Chu, HKBU 24 TCP/IP Protocols COMP4690, by Dr Xiaowen Chu, HKBU 25 OSI vs. TCP/IP COMP4690, by Dr Xiaowen Chu, HKBU 26 Network Components WAN PSTN LAN ROUTER 10BASE2 Segment HU B PROBE 2 SWITCH 2 WS 2 Router SERVER SWITCH 1 NMS PROBE 1 WS 1 SUBNET 2 Probe = Remote Monit or WS = Workstation PSTN = Publi c Switched Telephone Network NMS = Network Manage ment System = ne twork links = manage ment link s COMP4690, by Dr Xiaowen Chu, HKBU SUBNET 1 27 Repeater Hub Repeater is a physical layer device Hub is a repeater with multiple I/O ports Amplifies the signal Can extend the length of the LAN A physical layer device Demo network has a hub in subnet 2 Sometimes called “repeater hub” Repeaters and Hubs work at Physical layer. The bandwidth is shared by all attached devices. COMP4690, by Dr Xiaowen Chu, HKBU 28 Repeater Hub: topology COMP4690, by Dr Xiaowen Chu, HKBU 29 Repeater Hub: schematic COMP4690, by Dr Xiaowen Chu, HKBU 30 Bridge and Switch Bridge is a Link layer device Only forwards frame onto appropriate link(s) “Transparent” since self-learning Sometimes called “bridge hub” A switch is a multiport bridge So a switch is a layer 2 device In “switched Ethernet”, can have simultaneous comm. between hosts on LAN without collisions Sometimes called “switch hub” COMP4690, by Dr Xiaowen Chu, HKBU 31 Bridge Hub COMP4690, by Dr Xiaowen Chu, HKBU 32 Multiport Bridge Hub COMP4690, by Dr Xiaowen Chu, HKBU 33 Cisco Catalyst 2950 Series Switches COMP4690, by Dr Xiaowen Chu, HKBU 34 Performance •Some main performance metrics: •Backplane bandwidth: measured in bps (bits per second) •Forwarding capability: measured in pps (packets per second) •Number of MAC address •13.6 Gbps switching fabric •Cisco Catalyst 2955T-12: 6.4 Gbps maximum forwarding bandwidth •Cisco Catalyst 2955C-12: 2.8 Gbps maximum forwarding bandwidth (Forwarding rates based on 64-byte packets) •Cisco Catalyst 2955T-12: 4.8 Mpps wire speed forwarding rate •Cisco Catalyst 2955C-12: 2.0 Mpps wire speed forwarding rate •Configurable up to 8000 MAC addresses COMP4690, by Dr Xiaowen Chu, HKBU 35 Cisco Catalyst 6500 Series Switches COMP4690, by Dr Xiaowen Chu, HKBU 36 Performance Backplane Bandwidth 32-Gbps shared bus 256-Gbps switch fabric 720-Gbps switch fabric Layer 3 Forwarding Performance Cisco Catalyst 6500 Supervisor Engine 1A Multilayer Switch Feature Card (MSFC2): 15 Mpps Catalyst 6500 Supervisor Engine 2 MSFC2: up to 210 Mpps Catalyst 6500 Supervisor Engine 32 MSFC2a: 15 Mpps Catalyst 6500 Supervisor Engine 720: up to 400 Mpps COMP4690, by Dr Xiaowen Chu, HKBU 37 IP Router Routers Layer 3 devices Like bridges/switches, routers isolate collision domains Routers also isolate broadcast domains Routing tables use IP address For small network, static table is OK For larger network, use RIP, OSPF, etc. COMP4690, by Dr Xiaowen Chu, HKBU 38 Router: Framework COMP4690, by Dr Xiaowen Chu, HKBU 39 Bus-based Router COMP4690, by Dr Xiaowen Chu, HKBU 40 Switch-based Router COMP4690, by Dr Xiaowen Chu, HKBU 41 Cisco 7600 Series Routers COMP4690, by Dr Xiaowen Chu, HKBU 42 Performance Model 7603 7606 7609 7613 Slots 3 6 9 13 Forwarding Performance 15 Mpps 30 Mpps 30 Mpps 30 Mpps Backplane Capacity 240 Gbps 480 Gbps 720 Gbps 720 Gbps COMP4690, by Dr Xiaowen Chu, HKBU 43 Cisco 12000 Series Routers COMP4690, by Dr Xiaowen Chu, HKBU 44 Performance Modle Switching Capacity 12816 1.28 Tbps 12810 800 Gbps 12416 320 Gbps 12410 200 Gbps 12406 120 Gbps 12404 80 Gbps 12016 80 Gbps 12010 50 Gbps 12006 30 Gbps COMP4690, by Dr Xiaowen Chu, HKBU 45 Juniper’s Router Platform Throughput Max Forwarding Rate T320 320 Gbps 385 Mpps T640 640 Gbps 770 Mpps COMP4690, by Dr Xiaowen Chu, HKBU 46 Probes Probes Gather information and pass it to “management station” Management station analyzes the network traffic Probe is also called “remote monitor” In demo network, Probe 1 can monitor two segments simultaneously because it has two monitor ports. Also there are software-based probes COMP4690, by Dr Xiaowen Chu, HKBU 47 References J. Richard Durke, Network Management, Concepts and Practice: A Hands-on Approach, Prentice Hall, 2004. William Stallings, Data and Computer Communications, 7th Edition, Prentice Hall, 2004. J. F. Kurose and K. W. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, 3nd Edition, Prentice Hall, 2005. Fred Halsall, Computer Networking and the Internet, 5th Edition, Addison Wesley, 2005. http://www.cisco.com http://www.juniper.net COMP4690, by Dr Xiaowen Chu, HKBU 48