Switch infrastructure design - lots of small home switches in school

[gh5000]

Hi guys,

 

Just started in a new school in the past few months. The switch design here is on the whole pretty standard - core switch with fibre links to edge switches. However, in quite a few rooms they have little dlink/netgear 5 port switches that are used when the room only has one network point but they need a phone, access point and PC all in there (instead of running extra cabling).

 

Obviously this is the cheaper option but in my head it's detrimental to the performance of the wired network. Unfortunately I don't have the knowledge to back this up. I know I'm about to be asked to install 4 computers into a staff work area with only 1 LAN point. So was wondering if adding a small network switch in that room (which will be what the school will want to do) will effect the speed/throughput of just those computers or will it have any effects on the broader wired network.

 

Or am I worrying about nothing?

 

Cheers

[IrritableTech]

Small switches had been well used in my current school when I first came here. It took a few years to get rid of them all.

 

You're switching the single connection between devices, so there is a detrimental effect on speed of all the devices connected - but you might not notice in most cases. The biggest issues are the fact that little switches don't have the resources to be plugged into large networks. Mac address tables quickly get filled for example - we had lots that crashed frequently. The other big issue is that power gets unplugged, cables get messed around with causing loops. The more wires in an area, generally the bigger the problems.

 

When we decided to VLAN our network we had to rethink the small switches on a large scale. We moved to using 'economisers'. One network cable split into two (obviously with each using four wires and therefore having a max connection of 100mbit) where we had to, but we've now got to the point where we have removed all but one or two pairs of these.

Edited July 29, 2015 by IrritableTech

[JordanT91]

In the day to day running on the PCs they are unlikely to max out the 1GbE connection.The only time I think you'd have any issues is maybe during deployments (WSUS patches, whole images via WDS, applications with GP or SCCM etc.) or if the users will be doing large file transfers. I'm assuming you don't have a stupidly fast internet connection? Having 5 port switches isn't ideal (I have many around school in the older rooms) but unless you have the funds to get some cabling done I wouldn't worry about it. If you start getting complaints ("these PCs take ages to log on compared to the other ones!") then look into the load on the NICs and if they are indeed being maxed out then consider your options. I think I have used PRTG for this purpose in the past.

 

Like IrritableTech said, it's likely your biggest issue will be users turning off the switches and wondering why they can't log in. You don't have that problem when you're plugged directly into the wall...

 

Edit: I don't mean check if the NICs themselves are being maxed, they won't be. Check if the total load going through the NICs adds up to or gets anywhere near to the theoretical limit of 128MB/s for a 1GbE connection.

Edited July 29, 2015 by JordanT91

[simonm]

The other thing about the small / soho switches is that often they are NOT managed, so that means you can't deploy Vlans, Spanning Tree etc. Also when they are hidden ( which they often are ) it can make troubleshooting quite interesting.

[CyberNerd]

I always say no for these reasons:

 

The network is THE number one thing you need to run; nothing works if the network doesn't.

Unmanaged cheap switches have poor chipsets. How do you know if the device is spewing random data onto your network?

Poor diagnostics - if something goes wrong you've got very little chance on finding out what.

No VLAN's mean you are asking for trouble when it comes to future expansion, VOIP, QOS - nope

STP would become a nightmare.

Loops ?

Random network equipment going offline because someone unplugged it.

 

In short - lots (even a policy of having any) is a quick way to having an unserviceable mess of a network.

[win]

Better to run them all back to a network cabinet. If it's too far and budgets are tight then you can get a mini managed switch, i doubt they will notice a performance drop unless all 4 are in heavy use at the same time.

[dhicks]

However, in quite a few rooms they have little dlink/netgear 5 port switches that are used when the room only has one network point but they need a phone, access point and PC all in there (instead of running extra cabling).

 

If a room has a wireless access point then you should get a strong wireless signal in that room, hence you could do away with wired connections for the PCs in that room. If you're using VOIP phones (as you seem to be), you could use phones that have a pass-through ethernet port - either connect the wireless access point through the phone or the phone through the wireless access point.