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Solution
 
◆Switching and Routing(1)
  Bridging or routing? The age-old networking debate keeps resurfacing as network managers assess the speed, simplicity and lower cost of Layer 2 switching (bridging) against the greater network control afforded by routing technology.

In the wide area, the high recurring costs and relatively low speed of WAN links make it easy to justify the cost and management burdens of routers, These “general purpose” routers were often adopted in the campus, but frequently, “front-ended” routers providing significant price/performance and density advantages.

However, new requirements emerging in the campus are challenging this arrangement. A renewed focus on network control reflects how networks have grown-in both size and importance-and how responses to familiar like broadcast containment, security and support for complex topologies have changed since routers fist came on the scene.

At the same time, exploding bandwidth demands have les to the evolution in LAN technologies, such as Gigabit Ethernet. Since high-speed technologies like Gigabit Ethernet. Since high-speed technologies like Gigabit Ethernet will put additional pressure on the forwarding requirements of the core and surrounding devices, the big question in the industry is whether traditional will be able to keep pace.

The performance gap-in both throughput and packet processing-between high performance LAN switches and general-purpose routers in the campus enterprise network is widening fast, Other issues contribute to this mismatch

     With the rise of corporate intranets, unpredictable “any-to-any” traffic patterns are replacing standard“80% local1/20% backbone” traffic planning assumptions 

     Class and quality of service guarantees are needed to support emerging multimedia services without affecting response times of existing mission-critical applications.

     Organizations need to leverage their existing network infrastructures while simultaneously “future-proofing” new investments

What’s emerged in reaction to all of this is cacophony of new buzzwords and solutions, including “IP switching.” “cutthrough routing,” and a new focus on a class of products known as Layer 3 switches. So what’s behind these techniques? What value do they bring? Which is the right approach? As usual, network managers cannot assume a “one size fits all” solution for network control--there are tradeoffs to be made. These tradeoffs can be examined by organizing the various approaches into a taxonomy (classification).

 Switch Everywhere

The “switch everywhere” approach moves the routing function out of the LAN entirely, routing is applied only to WAN connections. Since all LAN traffic is switched, this is the highest-performance and lowest-cost option, it “flattens” the network-i. e, it removes subnets-and allows end stations access to any part of the LAN without router latencies of controls, Certain aspects of network management, particularly adds/moves/changes, are greatly simplified, since and station addressing is independent of physical location.

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