OK, so do I need a switch or a hub?

[zzaxx99]

At the moment, my network looks like this:

[  Router ] --------------------------------- [ ADSL Modem ] ---/--------------- ISP
 |  |  |  +-- Wireless 54g
 |  |  |    
 |  |  |    
 |  |  +-PC1
 |  |
 |  +-Laptop
 |
 +-Printer

I need to add 1 or 2 more machines to the network - what's the best way of doing it?

• Add a hub and plug the new PC and the laptop into the hub, and then the hub into the router?
• Add a switch in the same configuration?
• Add a switch between the router and Modem, and plug all the wired connections into that, leaving the Router as effectively a wireless access point?

The DHCP service is provided by the modem, operating in router mode (just to muddy the waters), which provides NAT and a single connection to the network.

(In the greater scheme of things, if I didn't have a broken port on the router, I could just use that, but only 4 of the 5 connections on there work - the ADSL link is broken so the modem is plugged into 1 of the LAN connections)

In normal cases, a switch would appear to be preferable to a hub, due to the superior performance, but will having the switch and router in the same path cause problems if I end up with (say) this:

[  Router ] --------------------------------- [ ADSL Modem ] ---/--------------- ISP
 | | +-- Wireless 54g
 | |    
 | |    
 | +-------  [ switch ]
 |                 | | |
 |                 | | +-Laptop
 |                 | |
 +-Printer         | +- PC1
                   | 
                   +- PC2

or would I be better off with:

[  Router ] ------------------------- [ switch ] ---------- [ ADSL Modem ] ---/------- ISP
    +--***                            | | | |
                                      | | | +- Laptop
                                      | | |   
                                      | | |+- PC1
                                      | |   
                                      | +- PC2
                                      |   
                                      +- Printer

Any networking gurus in the house?

(The laptop does have 54g wireless, but doesn't work for secure VPN link, hence the need for a wired connection)

 

[DaveJB]

A while since I did this sort of thing, but my first thought was 'why not plug into the router' until you mentioned the bust port. I'd have thought a simple hub would do it, it's hardly a mega network so the added capabilities of a switch aren't called for.... shame you're in London, I've got a spare hub and a spare switch in the spares box behind me, you could have tried both to check the hub's as good as a switch for what you want to do!

I'd best supply the standard caveat - it's about 5 years since I really had to do this sort of thing in earnest, and no doubt kit from one guy still doesn't like playing with stuff from another company, so it's best to make sure you can take it back and swap it if it doesn't work. As I recall my switch came from PC World, I was playing with networking a couple of years back for a book that never appeared, and it was only about £30 - 40 then, so it's not too expensive to get wrong at least!

Dave

 

[DaveJB]

Forgot the 'why' of it -
Switches are pretty well like hubs, but hubs just shout on every bit of cable going - hence ethernet has to retransmit packets due collisions now and then. Until you have a few machines on the go the collison percentage is small, so data rate hit on the ethernet isn't too bad, but you are basically sharing the data rate between "boxes that squawk" which becomes an issue if you have a bunch of busy PCs on the go. If busy, then the switch improves this markedly, as it knows which PC is on which port and can therefore avoid sharing bandwidth - so it comes down to 'how busy would the lines get' and 'divide 100 Mbit by number of PCs, is that still comfortably faster than my ADSL connection anyway?'
Dave

 

[zzaxx99]

Dave,

Thanks for the replies. The original cause of the question was that hubs seem to be in short supply at the moment, whereas as switches are, if not exactly 10 a penny, then pretty cheap. If a switch isn't going to get into a routing/switching argument with my router, then I'll head off to eBay and buy a switch.

 

[zzaxx99]

Good resource for networking FAQs

In passing, for the benefit of anyone else who happens to be interested in this subject, if you type "what difference ethernet switch hub" into AskJeeves, the first link you get back is What is the difference between an Ethernet hub and switch?, which pretty comprehensively answers the question. Lots of other good FAQs on that site as well.

 

[DaveJB]

Okay, no problems there then -
Ethernet switches are brighter than hubs, they stayed on for 6th form etc. I ran a network LAN on a UK WAN a few years back, with occasional extras joining in via phone line for short periods, and the ethernet would sort itself out fairly well - it's actually one of those things where you do a course on it and come away thinking 'I really must get a packet analysis app to play with' as a result of spending all week in a room of fellow incipient geeks.
Devices shouldn't conflict, note 'shouldn't' <g> although as you are no doubt already familiar Ethernet devices can be a bit annoying to get going at first... these days I just have it for ADSL modem into a Wifi/router for my small home network (doesn't EVERYONE have one?) and every time the ISP plays silly B****s I still end up interrogating IP addresses to see if it's an internal error...

Good luck!
Dave

 

[Blether]

Just to dot i's and cross t's, the gold standard for security says it's a good idea to have a switch (and not a repeater, aka hub) between your WAN router and [everything else on your network] as in your final diagram. It means you don't have LAN traffic and WAN traffic present in any single box - 'strength in depth' against the chance of your WAN router being compromised.

I don't find it keeps me awake at nights, but YMMV

 

[zzaxx99]

Well I went with organisation ( 1), with a switch - only to then fry my wireless router by plugging the wrong power* cable into it

(* ie the cable from the transformer - it wanted 3.3v and was very unhappy about having my 12v laptop connector plugged in. Exit one router)

Still I've now gained the one extra port I needed immediately, just don't have wireless any more.

Still can't get my new machine to talk to the network, but that's another story...

 

[DaveJB]

We had a chap at work plugged a Lexmark inkjet supply (about 15ft to a side as I remember, but probably a bit smaller in reality) in place of the Fujitsu dinky little one the laptop was expecting, and he fried about £900 worth of fiddly bits.
The surviving set of 8 laptops, power supplies, printers etc were then clearly marked with coloured tape labelled appropriately <g> Bit of a sod, but at least a new router won't cost too much these days. If you get stuck put coloured ribbons/tape/tags on the cable ends to identify which is which.
Dave

 

[dippy46]

Hi all, if it helps anyone, when I need extra ports on my router, ie: i've an extra computer to test or something I just plug a cheapy switch into one of the router ports (making sure its got the right psu)
then I have another 4 ports to play with. The router seems to handle everything OK thru DHCP. These little 5 port boxes can be purchased for as little as £10-12.
QED.

 

[dippy46]

Hi all, Yeh I should have looked more closely at the original diagrams, cos the second one ain't gonna work. It must be appreciated that it's the router that does the DHCP, So it must be
ADSL -------> ROUTER -------- PORT OUT1
-------- PORT OUT2
--------- port out nn --------- SWITCH --------------- PORT OUT1
---------------- PORT OUT2
AD NAUSEAM

"Simple ideas lie within reach only of complex minds"

 

[zzaxx99]

Not (necessarily) true actually - in my system, the "modem" is actually a router/modem, and it provides the DHCP.

Though, having said that, it doesn't seem to work on my new PC, and I've had to hardwire an IP address on it.

 

[DaveJB]

The 'middle' diagram looks iffy, in that the switch works becaue it knows which ethernet address (ie which device) is attached to which port - hence in this diagram the switch has the modem, router, and printer all in one port. given that I've not had to combine Ethernet with Wifi to any great extent and may therefore be amiss, I'd have thought the logical method would be to connect the modem to the router, the router to one port on the switch. The printer and other computers go into seperate ports on the switch also.
Dave