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Network Device Presentation


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Network Device Presentation

  1. 1. Chapter Overview <ul><li>Bridging </li></ul><ul><li>Switching </li></ul><ul><li>Routing </li></ul>
  2. 2. What Is a Bridge? <ul><li>A data-link layer device that connects networks and filters packets </li></ul><ul><ul><li>Propagates only packets destined for the other side of the bridge </li></ul></ul><ul><ul><li>Can reduce network traffic and collisions </li></ul></ul><ul><ul><li>Can lessen delays </li></ul></ul>
  3. 3. Connecting LANs with a Bridge
  4. 4. Bridges and Collisions <ul><li>A collision domain is a network (or part of a network) that is constructed so that a collision occurs when two computers transmit packets at precisely the same time. </li></ul><ul><li>Adding a hub to a local area network (LAN) increases its size but maintains a single collision domain because hubs relay signals immediately at the physical layer, without filtering them. </li></ul><ul><ul><li>Hubs do not relay packets immediately; they wait until the entire packet is received. </li></ul></ul><ul><li>Because the bridge delays propagation, computers on opposite sides of the bridge transmitting at the same time do not cause a collision. </li></ul><ul><li>Adding a bridge to a LAN splits it into two collision domains, resulting in fewer collisions and increased efficiency. </li></ul>
  5. 5. Broadcasts
  6. 6. Bridges and Broadcasts <ul><li>Bridges propagate all broadcast packets without filtering them. </li></ul><ul><li>The network segments on either side of a bridge are in the same broadcast domain. </li></ul>
  7. 7. Transparent Bridging <ul><li>Transparent bridging is a method for automatically compiling a bridge’s address tables. </li></ul><ul><li>Bridges maintain an address table for each network segment. </li></ul><ul><li>Bridges read the source and destination addresses of packets and compare them to the tables to determine whether to propagate them. </li></ul><ul><li>When a bridge lacks the information needed to filter a packet, it propagates the packet by default. </li></ul>
  8. 8. Bridge Types <ul><li>Local bridge. Connects network segments of the same type and at the same location </li></ul><ul><li>Translation bridge. Connects network segments at the same location that use different media or different protocols </li></ul><ul><li>Remote bridge. Connects network segments at remote locations, using a wide area network (WAN) link </li></ul>
  9. 9. Translation Bridge
  10. 10. Switch Characteristics <ul><li>Data-link layer device </li></ul><ul><li>Replaces bridges and sometimes routers </li></ul><ul><li>Similar in appearance to a hub </li></ul><ul><li>Forwards incoming traffic out to the destination port only </li></ul><ul><li>Converts a shared network medium to a dedicated one </li></ul><ul><li>Offers advantages such as reduced network congestion and the use of full network bandwidth </li></ul><ul><li>Can operate in full-duplex mode </li></ul>
  11. 11. Switching
  12. 12. Replacing Routers with Switches
  13. 13. Virtual LANs <ul><li>A virtual LAN (VLAN) is a subnet that exists inside a switch. </li></ul><ul><li>Broadcasts sent by a computer go only to the other computers in the VLAN. </li></ul><ul><li>Communications within a VLAN are switched. </li></ul><ul><li>Communications between VLANs can be routed or switched. </li></ul>
  14. 14. Layer 3 Switching <ul><li>Layer 3 switching minimizes the amount of routing between VLANs because routing occurs only when absolutely necessary. </li></ul><ul><li>A router establishes a connection between systems and then switches take over. </li></ul>
  15. 15. Switch Types <ul><li>A cut-through switch begins to forward packets immediately. </li></ul><ul><li>A store-and-forward switch waits until the entire packet arrives before forwarding it. </li></ul>
  16. 16. Router Characteristics <ul><li>Connect networks together to form an internetwork </li></ul><ul><li>Are network layer devices </li></ul><ul><li>Can connect LANs running different data-link layer protocols </li></ul>
  17. 17. Router Functions <ul><li>Forward packets to the destination network </li></ul><ul><li>Strip the data-link layer frames from incoming packets and repackage the data into new frames </li></ul><ul><li>Fragment packets when necessary </li></ul>
  18. 18. Routing Process Example
  19. 19. Hops
  20. 20. Routing Tables <ul><li>Routing tables are essential to the router operation and functions. </li></ul><ul><li>There are two methods of creating routing tables: </li></ul><ul><ul><li>Static routing. Manual creation of routing table entries by an administrator </li></ul></ul><ul><ul><li>Dynamic routing. Automatic creation of routing table entries by using a specialized routing protocol </li></ul></ul>
  21. 21. Router Types <ul><li>Routers can be stand-alone hardware devices or software running on a computer. </li></ul><ul><ul><li>Hardware routers. Range from expensive rack-mounted devices to small stand-alone units </li></ul></ul><ul><ul><li>Software routers. Include Microsoft Windows 2000 Internet Connection Sharing (ICS), and Routing and Remote Access </li></ul></ul>
  22. 22. Chapter Summary <ul><li>Bridging </li></ul><ul><ul><li>Bridges selectively relay packets between network segments, depending on their data-link layer destination addresses. </li></ul></ul><ul><ul><li>Bridges maintain a single broadcast domain and create separate collision domains. </li></ul></ul><ul><li>Switching </li></ul><ul><ul><li>Switches improve on the function of bridges by forwarding packets only to their destination systems. </li></ul></ul><ul><ul><li>Switches reduce the collisions on a network and increase the bandwidth available to each computer. </li></ul></ul><ul><li>Routing </li></ul><ul><ul><li>Routers are used to connect networks together at the network layer of the OSI reference model. </li></ul></ul><ul><ul><li>Routers strip away the data-link layer frame of incoming packets and build a new frame using the data-link layer protocol of the outgoing network. </li></ul></ul><ul><ul><li>Routing tables can be created manually by a network administrator or automatically by a routing protocol. </li></ul></ul>