At 2:43 PM +0000 3/13/03, Peter van Oene wrote: >At 10:44 PM 3/12/2003 +0000, Orlando, Jr. Palomar wrote: >>Without consulting any documentation, a couple of reasons I could think of >>is forwarding rate and the switch-fabric (or the size of the backplane, >>usually in Gbps). A full-fledged Layer-3 switch running at "wire-speed" >>would be much more efficient in routing (and switching) between VLANs >>compared to a router. > >Many routers route at wire speed and can do this on/between tagged >VLANs. This is just routing. > >>Another point of comparison is port density. You can only have such and such >>number of ethernet, fastethernet, or maybe even gigabit ethernet ports on a >>router before the cost becomes quite prohibitive. >> >>Oh sure, you can use the "router-on-a-stick" method. And though it is a good >>Cisco IOS feature, it was meant to be an interim solution when transitioning >>from a flat to a segmented network. >> >>Anyway, if you only have a relatively small network, say 2 VLANs, you can >>opt for the "router-on-a-stick" method. Or better yet, use a router with >>dual ethernets or fastethernets. However, if you're supporting 4,5, or more > >networks, that's what L-3 and multi-layer switches are for. >
Peter, would you agree that when someone says "that's what layer3 and multilayer switches are for," they are really talking about router packaging (as oppposed to fundamentally different technology) that creates platforms with certain port densities, functionality tradeoffs, and price points? Again, I call attention to the comment of "routing in hardware" as misleading. I can't think of a "routing ASIC," where I actually looked at the chip or chipset design, that wasn't some flavor of Von Neumann stored-program computer. Certain of the specific designs might be microcode rather than RISC or CISC, but they are still basically von Neumann. FPGAs might be a special case, but they can't do the more complex functions. In other words, an ASIC is a computer, just a specialized, optimized computer burned into silicon (or whatever).. Some newer ASICs even are partially reprogrammable, typically with electrically alterable gate arrays and the like. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=65330&t=65215 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
