I got into this discussion kind of late, but here's my take: Functionally, you can configure either to do what you want. But a 1 armed router has a couple major limitations that a layer 3 switch doesn't. A layer 3 switch has ASICs (application specific integrated chip/circuit) that can perform MAC re-writes, RIB/FIB lookups, rate-limiting, QOS, and ACL at wire speed without bothering the CPU of the device. A 1 armed router needs to use the CPU for some of these functions, and will quickly become a bottleneck after a certain level of traffic is passing through. Also, a 1 armed router is limited by it's 1 arm :) That link will be limited to 100 mb/sec (unless you move up to a 72xx or higher router, where gig is possible). So for instance if you're copying a large file between VLANs, it'd be pretty easy to use up all the bandwidth of that 100 mbit full duplex link, even if the CPU wasn't working hard on the 1 armed router. Moving to a layer 3 switch typically bumps that layer 3 device to layer 2 backplane a multi-gigabit speed connection. So if your traffic between vlans will ever exceed 100 mbit, you can either shell out huge bucks for a 72xx, or get a real QOS-friendly 3550 that is both faster and cheaper. Of course if you need WAN modules in the device that's another story. I was sent this chart a while ago listing speeds of various routers and switches:
> Router Performance Specs > > Router Switching Performance - Performance based on 64 Byte packets > > Platform Process Fast Fast > Switching Switching Switching > (PPS) (Mb/S) > ------------------------------------------------------- > 1400 600 4,000 2,048,000 > 1600 600 4,000 2,048,000 > 1700 1,500 8,400 4,300,800 > 2500 800 4,400 2,252,800 > 261X 1,500 15,000 7,680,000 > 262X 1,500 25,000 12,800,000 > 265X 2,000 37,000 18,944,000 > 3620 2,000 40,000 20,480,000 > 3640 4,000 80,000 40,960,000 > 3660 12,000 120,000 61,440,000 > MC3810 2,000 10,000 5,120,000 > 4000 1,800 14,000 7,168,000 > 4500 5,000 40,000 20,480,000 > 4700 7,000 50,000 25,600,000 > 7120 13,000 175,000 89,600,000 > 7140 20,000 300,000 153,600,000 > 7200-NPE100 7,000 100,000 51,200,000 > 7200-NPE150 10,000 150,000 76,800,000 > 7200-NPE175 9,000 175,000 89,600,000 > 7200-NPE200 13,000 200,000 102,400,000 > 7200-NPE225 13,000 225,000 115,200,000 > 7200-NPE300 20,000 300,000 153,600,000 > 7200-NPE400 20,000 400,000 204,800,000 > 7200-NSE-1 20,000 300,000 153,600,000 > uBR-NPE150 10,000 100,000 51,200,000 > uBR-NPE200 13,000 150,000 76,800,000 > 7000-RP 2,500 30,000 15,360,000 > 7500-RSP2 5,000 220,000 112,640,000 > 7500-RSP4 8,000 345,000 176,640,000 > 7500-RSP8 22,000 470,000 240,640,000 > Cat 2948G-L3 N/A 10,000,000 5,120,000,000 > Cat 4908G-L3 N/A 12,000,000 6,144,000,000 > Cat 4232-L3 N/A 6,000,000 3,072,000,000 > Cat -RSM 14,000 175,000 89,600,000 > Catalyst-RSFC 170,000 87,040,000 > Catalyst-RSFC/NFFCII 2,000,000 1,024,000,000 > Catalyst-MSFC (IP,IPX) 15,000,000 7,680,000,000 > Catalyst-MSFC (Other) 170,000 87,040,000 > Catalyst-MSFC2 (IP,IPX) 15,000,000 7,680,000,000 > Catalyst-MSFC2 (Other) 680,000 348,160,000 > Catalyst-MSFC (X-bar) 30,000,000 15,360,000,000 > > NOTE: VIP2 Distributed Switching significantly increases > the performance on RSP platforms. Chuck Church CCIE #8776, MCNE, MCSE >>>>Please advice if there are any difference in the >>> >>>functionalities etc. if I >>> >>>>use >>>> >>>>1) a L3 switch for routing between VLANs, >>>>2) a L2 switch followed by a router for routing >>> > between VLANs. > >>>1) define "functionality" >>> >>>2) define "difference" Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=62273&t=62273 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
