1 / 21

Network Devices

Network Devices. Repeaters, hubs, bridges, switches, routers, NIC’s. Devices and the layers at which they operate. NIC’s ( Network Interface Cards ). This NIC has interfaces for twisted pair, thicknet, and thinnet connectors. Repeaters.

marlow
Download Presentation

Network Devices

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. Network Devices Repeaters, hubs, bridges, switches, routers, NIC’s

  2. Devices and the layers at which they operate

  3. NIC’s (Network Interface Cards) • This NIC has interfaces for twisted pair, thicknet, and thinnet connectors.

  4. Repeaters • Signal attenuation or signal loss – signal degrades over distance • Repeaters clean, amplify, and resend signals that are weakened by long cable length. • Built-in to hubs or switches

  5. Hubs • OSI layer 1 hardware • Hubs regenerate and retime network signals • Hubs propagate signals through the network • They cannot filter network traffic • They cannot determine best path • They are used as network concentration points • They are really multi-port repeaters • Uplink port – crossover mode or straight through mode

  6. Bridges • A layer 2 device designed to create two or more LAN segments, each of which is a separate collision domain. • The purpose is to filter traffic on a LAN, to keep local traffic local, yet allow connectivity to other segments of the network. • Filter traffic by looking at the MAC address • Frame filtering

  7. Bridges • If the frame is addressed to a MAC address on the local side of the bridge, it is not forwarded to the other segment • MAC addresses on the other segment are forwarded • Bridges maintain a MAC address table for both segments they are connected to

  8. Cycle of bridges • Bridged network can span many segments • Broadcasts are sent to all segments

  9. BridgesDistributed Spanning Tree • If all bridges forward broadcasts, infinite loops can occur • Bridges perform DST on boot to determine which bridges will not forward broadcasts

  10. Switched networks • Shared ethernet networks perform best when kept to 30-40 percent full capacity • This is a result of CSMA/CD • A LAN switch is a high-speed multiport bridge which segments each port into its own collision domain and can access the full bandwidth

  11. Devices and the layers at which they operate

  12. Switches • Each port is a simulated segment to itself

  13. Store and Forward Switches • Do error checking on each frame after the entire frame has arrived into the switch • If the error checking algorithm determines there is no error, the switch looks in its MAC address table for the port to which to forward the destination device • Highly reliable because doesn’t forward bad frames • Slower than other types of switches because it holds on to each frame until it is completely received to check for errors before forwarding

  14. Cut Through Switch • Faster than store and forward because doesn’t perform error checking on frames • Reads address information for each frame as the frames enter the switch • After looking up the port of the destination device, frame is forwarded • Forwards bad frames • Performance penalty because bad frames can’t be used and replacement frames must be sent which creates additional traffic

  15. Fragment free cut through switch • Combines speed of cut through switch with error checking functionality • Forwards all frames initially, but determines that if a particular port is receiving too many bad frames, it reconfigures the port to store and forward mode • Preferred switching solution

  16. Unmanaged/Intelligent switches • Unmanaged – provides LAN’s with all the benefits of switching • Fine in small networks • Intelligent switches tracks and reports LAN performance statistics • Have a database ASIC (application specific integrated circuit) on board to collect and store data which you view through a software interface

  17. Layer 3 switch • By definition a switch filters or forwards frames based on MAC addresses. This makes a switch a layer 2 device. • Now we have layer 3 switches which have routing capability. If a data frame can’t be switched it is routed. • Each port is a separate LAN port, but the forwarding engine actually calculates and stores routes based on IP addresses, not MAC addresses • Usually support only IP or IP and IPX

  18. VLAN Switches • Virtual local area network • Each port on a switch defines a collision domain • The entire switch forms a single broadcast domain • VLANs can define multiple broadcast domains • Network traffic that is directed to all computers on the network can be segmented to transmit only on a specific VLAN. • Improves bandwidth on a the VLAN’s because each VLAN filters the network-to-network broadcast traffic as well as the collision traffic from other VLAN’s

  19. Physical Layer Broadcast • Physical layer broadcasts – implemented by non-switched Ethernet networks through shared cabling and hubs • Each bit that is transmitted is physically received by every station • Switches and VLAN’s don’t do physical layer broadcasts

  20. MAC-level broadcast • MAC-level broadcast – deal with how to handle MAC level broadcast frames; that is the data frames that have a broadcast destination MAC address • MAC-level broadcast frames are addressed to all MAC addresses on a given network (not a network segment, but an actual network as defined by its network address) • A regular switch forwards all broadcast frames out all ports, but a VLAN switch forwards broadcast frames only to ports that are part of the same VLAN • Multiple switches can be part of the same VLAN

  21. VLAN Switches • None of the VLAN’s can communicate unless each VLAN is connected to a router or layer 3 switch • Each VLAN is separating collision traffic associated with MAC Addresses (layer 2) and each VLAN is separating the network-to-network broadcast traffic. In other words each VLAN is acting as a separate network so a layer 3 device is necessary for them to communicate

More Related