VIEWS: 0 PAGES: 2 POSTED ON: 1/9/2013
Layer 3 Switching Presentation Michael DeBakey Layer 3 switching is an area that has been expanded upon and redefined with the proliferation of better quality processors commonly used in network equipment. Cisco refers to higher end routers as “switch routers” which move data across subnets from one interface to another. Traffic routed at the layer 3 level of the OSI model is comprised of a series of packets containing a source and a destination address, as opposed to frames that are transmitted at the layer 2 level. Is layer 3 switching a threat? Hardly. It has improved network performance drastically as routing algorithms and processor speeds improve. In addition, good network design theory plays into this naturally. By generously segmenting your network into partitioned network groups using Virtual LANs (VLANs) you then introduce inter- VLAN routing at the core by default. Routing is faster than layer 2 switching. Routers expand upon the idea of layer 3 switching and introduce more complex routing algorithms for use on backbone or WAN/MAN topologies. Layer 3 switching simply means the moving of packets from source to destination. A router (or layer 3 switch) has the ability to use different types of cabling, including ethernet, token ring, fibre optic, or even proprietary cabling used by certain vendors. Through one layer 3 device, connections can be bridged or aggregated (both of these being layer 2 operations) and then routed, though it is always preferable to have a router do nothing but route packets. Layer 3 switches come with a variety of features. They can cost anywhere from $30 for a consumer-grade Linksys router to millions of dollars for a well-implemented and fully redundant carrier class router such as the Cisco CRS-1. One of the biggest differences between these two devices (besides cost) is the type of connections they can handle. The CRS-1 handles Ethernet, but in addition it also handles fibre optic cabling, T1 interfaces, and other advanced circuits. The CRS-1 is also expandable by using additional blade modules for additional capacity. Implementation costs can run from nothing to around $2,000 for a day’s work by a network consulting firm such as ePlus. Cisco is the leader in layer 3 switching equipment. For what a school would need, a Cisco Catalyst 6509 switch would cost anywhere from $40,000 – $80,000 for the right modules including gigabit copper ports, SFP ports, and two supervisor blade modules. Typically one would want to enroll a Cisco product in a Smartnet contract for 24/7/365 support on the product. One would most likely implement a layer 3 switch in the MDF and collapse one building’s network into that MDF, allowing routing to take place back to the core network. All of these concepts are easily transferable to private industry, so there is no reason why a properly implemented solution in a K-12 networked environment could not be implemented equally well in a corporate environment (and vice versa).
"Layer 3 Switching Presentation"