Network Device Presentation

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