Connecting 2 switches to a router speed issue

December 9, 2010 at 07:04:52
Specs: Windows XP
I work in the computer graphics industry and use multiple computers connected together in a "farm" to produce images. Most of the computers are unattended "nodes". I have a small network connecting things together. All computers are hardwired gigabit with jumbo frames disabled. In the office (location A) I have 6 workstations, a router/gateway with wireless and an 8 port unmanaged gigabit switch with automatic MIDI/MIDI-X crossover detection. I have a CAT 6 cable going to another room where the "farm" and NAS file sever are located (location B). There is a 16 port unmanaged gigabit switch with automatic MIDI/MIDI-X crossover detection in this location.

Recently I re-wired location A. My network slowed to a crawl. In location A I had connected the router to the switch and then connected the switch in location B to the switch in A. I was getting connections in the 8 Mbps range. I then connected both switches directly to the router. My speed in B jumped to 87 Mbps. When I test the connection in location A I get 215 Mbps. I would like to get this connection speed at both locations. What can I do?

It seems strange that I had the problem connecting the two switches since they both have auto uploading.


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#1
December 9, 2010 at 08:14:03
Object is to have the least amount of downsteam switches.
Ideally both switches connect to the router not one to another.
When connecting one to another you want to consider trunking but this is usually achieved with a managed switch.

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#2
December 9, 2010 at 08:32:44
Thank you for your reply. That would explain why I had the slowdown. Any ideas why the connection is slower in location B now that they are connected correctly (87 Mbps compared to 215 Mbps? Both switches are the same grade, vintage and manufacture (Linksys).

I'm thinking about upgrading the router and switches if it will help with this issue. I want to maintain the highest bandwidth possible for both segments. I'm currently using SOHO grade equipment. I have moderate skills for networking but it seems like this is a simple setup.


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#3
December 9, 2010 at 10:06:04
I have know idea of what to look for to upgrade the switches and router. I suspect I'm looking for a managed switch and something that says it will output 2000 Mbps per port. Will upgrading these make a difference? Does anyone have a recommendation?

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#4
December 9, 2010 at 10:44:28
Did you do the wiring?

Appears the only thing you need to upgrade is the router so it has gigabit lan ports.

Do a seach on router with gigabit lan ports and see what comes up. I know linksys has one as may others. I am a fan of Netgear not linksys.

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#5
December 9, 2010 at 11:31:37
Yes. Most of it is Cat5.

Checked my router. It has T100. Could that be affecting the speed of my LAN?


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#6
December 9, 2010 at 12:15:09
Yes. Most of it is Cat5.

Cat5 or Cat5e?

There is a difference. Cat5 was never spec'd for 1000 Mbps (gigabit) whereas Cat5e is.

I'm told you can use Cat5 for 1000 Mbps but only in very short lengths. Personally, I wouldn't try to carry 1000 mbps on Cat5.

So if the cable in your walls is Cat5, you might want to give serious thought to upgrading it to Cat6.

Checked my router. It has T100

I'm not sure what you mean by T100 or what it references. Does this mean the LAN ports on it are 100 Mbps? If so, that would definitely slow things down.

Wanderer is correct about daisychaining switches. The reason you don't want to is that the bandwidth aggregates. Which is to say if you have 3 switches, 2 plugged into 1, and 3 plugged into 2 then you end up with the following:
- switch 2 carries the sum total bandwidth of switch 3 AND itself
- switch 1 carries the sum total bandwitch of both switches 2 and 3, as well as it's own.

Typically in industry we avoid daisychaining at all costs. But we deal in hundreds and thousands of clients and their bandwidth, not 10 to 20 which is not a whole lot in comparison.

However, it may be necessary for you to daisychain in your particular instance. If your router is maximum 100 Mbps to the LAN ports and you plug both your switches into it, any/all communication between switches would slow down to 100 Mbps. So if client A on switch 1 has to communicate to client D on switch 2, they pass through the 100 Mbps LAN ports on the router and that's your bandwidth for the communication.

Conversely, conversation between clients on the same switch should remain 1000 Mbps as long as they all have 1000 Mbps NIC's.

So, to sum up, you have two options if you want all LAN communication to be 1000 Mbps and the LAN ports on your router are maximum 100 Mbps.

1) Daisychain switch two into switch one. Switch one being plugged into a LAN port on the router

2) buy a third switch. Plug it into a LAN port on the router and plug switches 1 and 2 into it.

Option 2 is reasonable since if you don't plug any clients into it, it will only carry the bandwith of 1 and 2 and their clients only. This is essentially what the router is doing now, only if the router is 100 Mbps, it's doing it 10 times slower.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#7
December 9, 2010 at 12:16:20
Wiring is what I would suspect is the issue.

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#8
December 9, 2010 at 12:29:41
Thank you for all your help!

It's all CAT5e. The cable in the wall is CAT6.

The Router is 100 Mbps. So it makes sense that the connection between the two 1000 Mbps switches connected together using the router would be reduced to 100 Mbps. When I daisy chain the switches it reduces the speed to about 8 Mbps.

I'm thinking of upgrading the router to one with 1000 Mbps. It's a low end consumer grade unit that's 3 to 4 years old.


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#9
December 9, 2010 at 13:25:17
I'm thinking of upgrading the router to one with 1000 Mbps. It's a low end consumer grade unit that's 3 to 4 years old.

I'm pretty sure they make them with 1000 Mbps LAN ports so that should definitely make a difference.

If you don't mind me asking, did you have the wiring done professionally? Was the wiring tested and certified? The issue could easily be the wiring and testing/certifying is always done (by professionals) so that the person paying for the job can know it's all good.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#10
December 9, 2010 at 15:15:12
Curt,
Sorry I got the name wrong before. I'm getting a new router. I thought this one:
http://www.netgear.com/business/pro...

I have a small home based business so I do everything myself. The cables are all factory made. I suppose it's possible that there could be a bad cable somewhere. I've often wondered if there was a way to test the cables. I guess I can at least do a software speed test.


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#11
December 10, 2010 at 07:30:10
That looks like it should do the trick. I see it does have 4 Gigabit LAN ports.

If the cables are factory made, they should be ok. That's not a guarantee as I'm pretty sure they don't test each and every one.....but I have yet to have any bad factory cables that I can recall.

If you don't own a tester, don't worry about it. A good tester will cost about $1,000.00 (US) and if you're only going to use it to test a couple cables, well, it ain't worth it......lol.

Those cheap blinking light testers are useless. I've seen them show a cable as being "good" when it failed on a real tester. As I said, I wouldn't worry too much about them. You'll know once you do some data transfer tests.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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