Ch4_1 - Internetworking Network Layer Introduction Outline In the previous chapter we discussed techniques to overcome some of the limitations of

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1 Internetworking: Network Layer EE 281, Internetworking 2 Introduction & Outline z In the previous chapter, we discussed techniques to overcome some of the limitations of LAN, i.e., usage of bridges to extend LAN (packets can travel over geographically larger area/s) with better use of bandwidth (learning bridges, spanning tree). But still we had: – Heterogeneity: LANs of similar networks of similar addresses, Billion hosts Æ addressing problem, logical addresses z We also discussed how switches can forward packet, fast, between its ports. However we need to know how the switch/router can determine the best route or path of forwarding. What informatioin does it need to direct packets to their destinations… z In this chapter, we examine some approaches that address these problems and concerns. This would lead us to the design of internetworking (internet): arbitrary collection of networks(or LANS) interconnected by routers and other devices. (not to be confused with Internet.) z We will discuss the main aspects and relevant protocols which make the building of the internet feasible and efficient.
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2 EE 281, Internetworking 3 Router vs Switch z A key player in the implementation of the internet is a router z A router is a network-layer device. Its job is to move data between different network segments by looking into packet headers & determine the best path for the packet to travel. EE 281, Internetworking 4 IP Internet z Note:routers, not like bridges, can process packet header. z Using IP (Internet Protocol, that “ runs over anything”) routers can connect network segments that can use different technologies. It’s a key tool to build scalable, heterogeneous networks. R1 ETH FDDI IP IP ETH TCP R2 FDDI PPP IP R3 PPP ETH IP H1 IP ETH TCP H8 Example of Internet Journey of Pkt from H1 to H8. Note, IP protocol makes it all possible by being platform independent! H4 H5 H3 H1 Network 2 (Ethernet) Network 1 (Ethernet) H6 Network 3 (FDDI) Network 4 (point-to-point) H7 R3 H8 R2 R1
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3 EE 281, Internetworking 5 Pop Quiz Example: True or False: Routing occurs exclusively at OSI layer 3 and below, while switching occurs exclusively at OSI layer 2 and below. a. True b. False [Hint:While in routing, datagram forwarding decisions are based on OSI layer 3 information, and in switching, datagram forwarding decisions are based on OSI layer 2 information, the information still needs to be passed down to OSI layer 1 and transmitted over the physical media as a stream of bits.] EE 281, Internetworking 6 Router Hardware Front Fiew Rear View • A router can also be viewed as a special processor (CPU+Memory+Bus+OS) that forwards network traffic along optimized paths. It determines these optimized routes through the assistance of routing protocols. In this chapter, many of these protocols are discussed.
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4 EE 281, Internetworking 7 Internet Architecture: TCP/IP Suite z Defined by Internet Engineering Task Force (IETF) z Hourglass Architecture with four layers Telnet HTTP DNS TFTP TCP UDP IP NET 1 NET 2 NET n “Here all goes through me” EE 281, Internetworking 8 TCP/IP vs OSI Model
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This note was uploaded on 03/10/2009 for the course SDD sa taught by Professor Saf during the Spring '09 term at SUNY Adirondack.

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Ch4_1 - Internetworking Network Layer Introduction Outline In the previous chapter we discussed techniques to overcome some of the limitations of

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