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ROUTERS

ROUTERS. Raja Chandra Rangineni. AGENDA. DEFINITION ROUTER’S ARCHITECTURE TYPES GENERATIONS ALGORITHMS PROTOCOLS METRICS SIMULATION REFERENCES. DEFINITION. is a device that forwards packets along the networks - it is connected to at least two networks

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ROUTERS

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  1. ROUTERS Raja Chandra Rangineni

  2. AGENDA • DEFINITION • ROUTER’S ARCHITECTURE • TYPES • GENERATIONS • ALGORITHMS • PROTOCOLS • METRICS • SIMULATION • REFERENCES

  3. DEFINITION • is a device that forwards packets along the networks - it is connected to at least two networks - operates at the Network Layer of the OSI model - path determination and packet switching

  4. ROUTER ARCHITECTURE • Components: CPU ROM:Bootstrap, OS software Flash: Internetwork OS RAM: Routing tables,config files, cache, packet buffering NVRAM: Startup config files Interface Cards

  5. Data Hdr Data Hdr IP Address Next Hop Address Table Buffer Memory Generic Router Architecture Header Processing Lookup IP Address Update Header Queue Packet 1M prefixes Off-chip DRAM 1M packets Off-chip DRAM

  6. TYPES • Configuration: - Static Routers - configured manually - route packets based on information in routing tables - Dynamic Routers - uses dynamic routing algorithms link state, Distance vector

  7. TYPES • Point in Network •Corerouters high speed trunk connections •Distributionrouters higher port density, aggregating network edge to the network core •Accessrouters high port density, connecting the end users to the network •Borderrouters connections to other providers •Servicerouters hosting and servers

  8. CPU Buffer Memory Route Table CPU Line Interface Line Interface Line Interface Memory MAC MAC MAC Operates at 0.5Gb/s First Generation Router -Fixed Interface Centralized forwarding little equipment and small loads –1970’s Shared Backplane Line Interface

  9. Fwding Cache CPU Buffer Memory Second Generation Router Route Table - modularized interface and centralized forwarding - 1980’s - earlier,more users, more traffic but less interfaces, low bandwidth, low Processing speed - bottlenecks - operational capacity 5Gb/s - Now,use of cache, reduced Bus and CPU(single) use Line Card Line Card Line Card Buffer Memory Buffer Memory Buffer Memory Fwding Cache Fwding Cache MAC MAC MAC

  10. Fwding Table Third Generation Router -distributed processing and bus architecture • why? Switched Backplane routes could not always be found in the Cache due to increase in access scope - Here, Separate Routing and forwarding, service board could conduct independent route forwarding - use of Multi Processing Unit(MPU) - performance increased multi fold - 50Gb/s Line Card CPU Card Line Card Local Buffer Memory Local Buffer Memory Routing Table Line Interface CPU Memory Fwding Table MAC MAC

  11. Fourth Generation Router Optical links -Increase in use of web, web services, Commercialization of IP - traditional s/w routers couldn't meet the require- ments -shared memory on switching network -solved the problem of internal switching - 0.3-10 Tb/s Switch Core Linecards

  12. ALGORITHMS TYPES • Static - the tables are mapped by the administrator before routing begins Vs Dynamic - adjust to network changes, and update the tables: Link State,Dynamic Vector • Single Path – uses only single path for routing Vs Multi Path - traffic multiplexing over Multiple Line, also called load Sharing . Flat - Routers are peers for all others Vs Hierarchical - has domains or areas,only some routers in the domain can communicate with routers in other domain. . Host-Intelligent - The source end determines the route, routers are mere store and Vs forward devices Router-Intelligent - routers determine the path through the internetwork . Link-State - also known as Shortest path First. Each router builds a picture of the entire network in its routing tables. Food small updates everywhere Vs Distance Vector- call for each router to send all or some portion of its routing table, but only to its neighbors. Send larger updates only to neighboring routers

  13. PROTOCOLS • Routing protocols –protocols that implement routing algorithms. These build tables used in determination of path selection. Examples :Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF), Exterior Gateway Protocol (EGP), Border Gateway Protocol (BGP), Intermediate System-to-Intermediate System (IS-IS), and Routing Information Protocol (RIP). • Routed protocols –protocols that are routed over an internetwork Examples : Internet Protocol (IP), DECnet, AppleTalk, Novell NetWare, OSI, Banyan VINES, and Xerox Network System (XNS).

  14. METRICS • These are the basis on which the algorithms determine which route is preferable Some of the metrics commonly used are Path length Reliability Delay Bandwidth Load Communication cost • Some routing algorithms use multiple metrics, combining into a single hybrid metric.

  15. IP 47.1.1.1 SIMULATION 47.1 1 IP 47.1.1.1 2 IP 47.1.1.1 1 3 2 IP 47.1.1.1 1 47.2 3 47.3 2

  16. D D R3 R1 R4 D A B E R2 C R5 Destination Next Hop F D R3 E R3 F R5

  17. R3 R1 R4 D D A D D B E R2 C R5 F

  18. R3 R1 R4 D A B E R2 C R5 F

  19. REFERENCES • http://www.cisco.com/warp/public/707/21.html#intro • http://computer.howstuffworks.com/router8.htm • http://www.dummies.com/WileyCDA/DummiesArticle/id-2267.html • http://www.huawei.com/dcweb/app/view.do?id=46&pageId=46_1

  20. Queries

  21. Thank You..

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