1 / 17

Bridges, Hubs, and Switches

Bridges, Hubs, and Switches . Dijiang Huang. Extending the LAN. Why? Build larger (geographic) networks Communicate with more hosts Issues Signal Delay Signal Attenuation. Repeaters. A hardware device used to extend a LAN

lenci
Télécharger la présentation

Bridges, Hubs, and Switches

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bridges, Hubs, and Switches Dijiang Huang

  2. Extending the LAN • Why? • Build larger (geographic) networks • Communicate with more hosts • Issues • Signal Delay • Signal Attenuation

  3. Repeaters • A hardware device used to extend a LAN • It connects directly to the physical medium (no access units used). • It amplifies all electrical signals that it receives.

  4. Repeaters • Limitations: • It amplifies all signals that it receives including noise (e.g. lightening) • Operates at physical layer. It does not recognize any protocols - so it copies packet collisions as well as valid packets. • A problem on one segment is propagated to all other segments. All segments are in one collision domain • No more than 4 repeaters in a LAN

  5. Repeaters - Application Segment on Floor 3 R3 Riser Segment Segment on Floor 2 R2 Segment on Floor 1 R1

  6. Bridges • Used to extend the range of LAN segments • Operates at Data Link level. Connects to segments just like nodes. • It propagates only complete / correct packets. Each segment becomes its own collision domain

  7. Bridge - Application • Packet forwarding regenerates data signal. Phase shifts, noise, etc. are removed. • As packets are forwarded, bridge “learns” which hosts are on each segment.

  8. Planning Bridged Networks • Bridges only propagate packets that are destined for other segments. • It thus allows simultaneous communications between hosts on the same segments. • Traffic studies can optimize the design of segments such that most communications happens within a segment, not between segments.

  9. Bridged Network Segment A Segment B Segment D Segment C Segment E Segment F Segment G Segment H

  10. Cycle of Bridges • Infinite transmission path loops may occur. • Bridges decide whether to forward packets based on a distributed spanning tree algorithm (DST)

  11. Hubs • Passive Hubs • Mechanical connection only (no amplification) • Active Hubs • Provides regeneration of signal • Intelligent Hubs (Switching Hubs) • Adds traffic routing • May add network management capabilities.

  12. Hubs (Active Hubs) • Used with xBaseT Ethernet technologies. • Hub regenerates each bit. • Operates at physical level and amplifies signal • Also known as multi-port repeaters • Signals are forwarded to all other ports on the hub.

  13. 10BaseT Hub • Used to interconnect Hosts on a LAN

  14. Backbone Hub • Used to interconnect LANs • All segments are part of the same collision domain

  15. Switched Hubs (Switches) • Each port “learns” which hosts are connected to it • Only packets destined for those hosts are forwarded to that port. • Lower traffic load means fewer collisions, so higher throughput. • Since it uses an xBaseT 4-wire interface, it may support full duplex transmission.

  16. Switched Hub Architecture

  17. Summary • Repeaters • Used to extend length of segment • Bridges • Used to forward packets between LANs • Hubs • Used to interconnect hosts • Switches • Used to forward packets between Hosts / LANs

More Related