I think that what you have described is "multi-layer" switching. As Howard has mentioned in past posts, L3S is simply a marketing term as is wire-speed switching. Layer 3 Switching is simply a line card, typically in a chassis-based system, that can make routing decisions (layer 3) using hardware-based technology (layer 2). By not relying on the fundamentally slow software decision making, this process greatly enhances the speed at which the decisions are made. There are other types of L3S devices, such as a 2948G-L3. This switch uses ASICs to make routing decisions within hardware. When you purchase one of these beasts, you basically have a 48-port gigabit router! Inter-VLAN routing is just routing. Basically, it can be performed with any routing-capable device so long as you have the appropriate interfaces. The difference between Inter-VLAn routing and legacy routing really has nothing to do with routing at all. The real difference is how the LANs have been broken out: either Layer 2 (VLANs) or Layer 3 (IP subnetting). If you know something about routing, then you know something about Inter-VLAN routing. Read up on VLANs (I suggest the Kenndy Clark CCIE switching book) and all will become clear. Rik -----Original Message----- From: Gareth Hinton [mailto:[EMAIL PROTECTED]] Sent: Monday, May 28, 2001 6:09 AM To: [EMAIL PROTECTED] Subject: Re: What do "interVLAN routing "and" Layer 3 switching " mean [7:6104] Hi Frank, I think the best description for Layer 3 Switching is "Route once - Switch many". The first time a packet in a particular "flow" passes through, a routing function will be used (on a different card, or even in a different device). But to speed up the processing of any further packets in that flow, a cache is created in the switch to remember this flow. The next time a packet comes through which matches this flow it will be switched without using the router functionality, therefore speeding things up. The definition of a flow can differ depending on configuration. For instance, normally a flow may be any packet to a particular destination, but if , for example, an extended access list is configured, the criteria for the flow may tighten up i.e. to be considered part of a flow, the source and destination are compared. Inter-VLAN routing means a packet gets routed every time. Regards, Gaz ""frank"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > What does the following mean ?it's cut from a description of WS-X4232-L3 on > cisco website. > > > The Catalyst 4003 and 4006 Layer 3 Services module provides interVLAN > routing for the Catalyst 4000 family switch and provides Layer 3 switching > between the Gigabit Ethernet interfaces. > > "John Hardman" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Hi > > > > OK I'll bite... > > > > Yes there is a difference. It gets a little convoluted, but there is a > > difference. > > > > L3 switching: Think of a L3 switch as a multi port router that operates at > > wire speed. The 2948G-L3 is an example. It is just a 50 port Ethernet > > router. So L3 switching is routing traffic at wire speeds. You could use > one > > of these to route between VLANs, or route between networks. > > > > Inter-VLAN routing: This is a technique, technology that is only used to > > route traffic from one VLAN to other VLAN(s). It generally takes place at > > wire speeds inside a Cat switch with a L3 switch option, but is often see > > with routers that do not work at wire speeds. > > > > So the bottom line... think of a L3 switch as a device, and Inter-VLAN > > routing as a technology. > > > > HTH > > -- > > John Hardman CCNP MCSE > > > > > > ""frank"" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > Any difference? > > > > > > "frank" wrote in message > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > Thanks, > > > > > > > > > > > > Frank > > > > FAQ, list archives, and subscription info: > > > http://www.groupstudy.com/list/cisco.html > > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > FAQ, list archives, and subscription info: > > http://www.groupstudy.com/list/cisco.html > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=6124&t=6124 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
