Switches question

[t_chris53]

This may be a dumb question... but I need to know, and can't find the answer anywhere. When I look at the prices for a layer 2 switch, (whether Cisco or not), I find some are cheap (hundreds of dollars), and some are not (thousands of dollars). What is the real difference? why the huge gap? I heard some talk of a "back plane", or is it the load capability? I was looking for gigabit switches to replace my current 10/100's, so what is the technical difference from a switch under $1000 to one that is over $2000-3000?

[Richard Burts]

Tom

There might be some differences in hardware - what is the capacity of the back plane to move frames, how many ports can forward at line rate, is the forwarding truly non-blocking, how many entries are there in the switch forwarding table, etc. But the real differences are probably not in the hardware but in the supporting software and management services that the switch provides. Some of the low cost switches are non-managed - you can not log into them, you can not see the content of their switching table, you can not configure VLANs, you just plug devices into the ports and it does the rest. The better switches are managed and give you the ability to access them, to monitor them, and to configure aspects of their operation. There may also be differences in the services that they offer. Recently I was at a customer site where we wanted to capture some traffic. The particular switches that this customer was using had the ability to have only a single input port and a single output port for packet capture. Compare this with the flexibility that Cisco provides with SPAN and RSPAN and you see some of the reasons for the price difference. The lower cost switches are probably just layer 2 switches providing basic functionality while the more expensive switches may be layer 2/3 and provide more advanced functionality. The price difference also probably reflects the amount and the kind of support that the vendor supplies for the switches.

HTH

Rick

[andrew.burns]

Hi,

Very good question actually, why buy a Cisco 48-port gigabit switch for $5,000 when you can get an apparently similar Linksys 48-port gigabit switch for $800?

Both have a non-blocking architecture (i.e. all ports can forward at full line-rate simultaneously) and both appear at first sight to support all the necessary protocols (spanning tree, trunking, etc). However, when you go a bit deeper into your own current and future requirements a few other questions need to be answered:

1) Hardware Support (Cisco support is a no-brainer - buy a smartnet contract and keep it up to date. What does the other manufacturer offer?)

2) Software Support (How often do you get updates/bugfixes? can you get 24x7 telephone support? does the manufacturer have a TAC?)

3) Reliability (hot swap components/DC power capable?)

4) Current and future feature sets? (Does the switch support QoS? do you need it? what about security features? mobility? IP telephony?)

5) Integration with current or planned NMS (does it support syslog/ntp/snmp/aaa etc? )

The key is getting your requirements right - once you've done that you should be easily able to decide which one to go for.

HTH

Andrew.

[t_chris53]

Hmmm... here's another question, I've seen some switches, (24 port) with 32 or 48Gbps fabric (backplane), and then others with 115Gbps, still with only 24 ports. So how do I know a switch has a beefy enough backplane for top speed at full duplex for all ports simultaneously? Is there a calculation or standard (i.e. 2Gbps per port or what?).

Thanks for the responses so far..

Tom

[mark.cronin]

Tom

what is your current requirement?

Mark

[t_chris53]

I've got 120 users, 7 switches (on various floors and sections of the building), We currently are running a heavy document load (law firm), a couple databases, exchange 2003 environment, and in the future are looking forward to IP phones, and server based dictation/transcribing, (audio files..). So my worry is that my 10/100 structure will soon be struggling to bare the load. Hence my desire to upgrade my wiring/switching now. I suspect the phones will end up being a Cisco system, so as far as support goes, I believe Cisco will only support their switches, but I was noticing that some of them only had a 32Gbps backplane on a 48 port switch! I don't think that's going to be enough is it?