Layer 3 switching combines the best of switching and routing in one platform. The main advantage here is speed. The way it works is, in a switch you have some kind of layer 3 routing engine (aka route processor, or RP). For example, the MSFC2 (Multilayer Switch Feature Card 2) is one of the options available for the Cisco 6500 (and a couple of others, I think) switches. When the switch receives a packet bound for a different VLAN, it sends it to the RP. The RP makes the routing decision and puts an entry in the route cache for the switch. The first packet in a flow is routed and the rest are switched at wire speed, hence the increase in speed. That's kind of a simplified view, but I think it gets the general idea across. So, layer 3 switching is both routing and switching, but faster (usually, anyway).
""DeVoe, Charles (PKI)"" wrote in message news:[EMAIL PROTECTED] > I am under the impression that switching is a layer 2 function and that > routing is a layer 3 function. I have seen several discussions talking > about layer 3 switching. Could someone explain this to me? Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=63738&t=63728 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
