Week 5 lan topology part 2
- 1. Introduction to Networking Technologies Assembled By David Roberts Knowing what you DON’T know is more important than what you DO know. It takes both to have expertise.
- 2. Introduction to Cisco Networking Technologies • Network Topologies.
- 3. Bus Topology • Use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. • A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message. • Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. • Bus networks work best with a limited number of devices. • If the backbone cable fails, the entire network effectively becomes unusable.
- 4. Ring Topology • In a ring network, every device has exactly two neighbors for communication purposes. • All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). • A failure in any cable or device breaks the loop and can take down the entire network. • To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.
- 5. Star Topology • A star network features a central connection point called a "hub" that may be a hub, switch or router. • Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet. • A star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
- 6. Tree Topology • Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. • This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
- 7. Mesh Topology • Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. • Some WANs, most notably the Internet, employ mesh routing. A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.
- 8. Summary • Topologies remain an important part of network design theory. You can probably build a home or small business network without understanding the difference between a bus design and a star design, but understanding the concepts behind these gives you a deeper understanding of important elements like hubs, broadcasts, and routes.
- 9. OSI
- 10. OSI
- 11. Connecting Networks Device OSI Layer Notes Repeater Physical (#1) Two types: amplifiers and regenerators. Boosts signals. Bridge Data Link (#2) Use to segment Networks running NetBEUI (Sportack, p.131) which is not routable and cannot be used with routers.Suitable for smaller, simpler networks because it uses only the MAC address whereas routers use the network addresses (e.g. IP) which contain information about how the network should be logically segmented.Can join only segments using the same data-link protocols, i.e. Ethernet to Ethernet, Token to Token, etc. Router Network (#3) Good for connecting dissimilar data link layer protocols (Ethernet - Token Ring - etc.)Compression and fewer bits mean fast data transfer. Brouter Network (#3)and Data Link (#2) Forwards based on logical address for routable protocols and on physical address for non-routable protocols. Switch Data Link (#2) Uses MAC addreses. Gateway Multiple Translates, converts, and repackages data between dissimilar networks. Usually software on a PC.