Cascading ethernet switches - what's the catch?

[zarn]

I'm putting in a new switch for my home network. Right now, 8 ports is plenty; in future, I'll need 16 or maybe even 24. In the range I'm buying, the 8 port switch is about £40, but the 16 port is £105, and the 24 port about £180. Rather than buying big now to protect for the future, it's cheaper to buy small, and add more 8 port switches in future.

To make this work, I'll need to cascade the switches. All the kit is gigabit ethernet, which is way faster than I expect to need for domestic use, so I don't expect any bottlenecks. Is this OK, or is there a catch? Have I missed something? I'm struggling to see why the bigger switches cost more per port.

[directhex]

The catch is the bottleneck points - e.g. 7 devices would be sharing a single gigabit link into a second switch

[TheAnimus]

Always remember too that many switches can't switch all the ports simulataniously.

If you've got 8*1gb ports, you might well if you've a 4gb total limit.

The more expensive the bigger switch often allows more total throughput.

[smargh]

Two words:

broadcast storm

http://en.wikipedia.org/wiki/Broadcast_storm

[Steve]

I can't see anybody being able to broadcast storm his home network, smargh.

Bottlenecking is the biggest issue, but depending on your needs, it mightn't be an issue.

[smargh]

Most commonly the cause is a redundant switched topology where a loop exists in the Ethernet wiring topology (i.e. two or more links exist between switches). As broadcasts and multicasts are forwarded by switches out every port, the two switches will broadcast each other's broadcasts - creating a switching loop.

Most easily identified by lots of blinking lights.

[zarn]

Thanks for all the input. Based on this, I'm sticking with the 8 port, and will be careful not to create loops in the cascade. The model I'm looking at (a D-Link green ethernet, model DGS-1008D) claims to have a 16Gb "switching fabric", which I'm assuming means it won't be a problem providing full speed to all 8 ports?

[mdjmcnally]

What I would do after you get above 2 switches is take one of them and use as a central switch

ie instead of

Switch
|
Switch
|
Switch
|
Switch

Go

Switch
| | |
Switch | Switch
|
Switch

Providing the total distance between any 2 machines is less then 200metres of cable then won't be a problem.

This way as well then won't need to run up through all of the switches. Most will need to do is through 3.

[Funkstar]

                  Switch
                 |   |   |
            Switch   |   Switch
                     |
                    Switch

Or like this

[mdjmcnally]

Thats how it displayed when I typed in, however it posted strangely.

Would have posted as an attachment but my post count isn't high enough.

[Funkstar]

Just wrap things like that in [ code][/code ] blocks. HTML doesn't handle multiple spaces for layout be default.