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Upgrading to a gigabit lan

I wish to upgrade my small office network to 1 gigabit, however I readlly do not want to go through the big hassles of changing the cables (Cat 5) just yet.

If I upgreade routers/switches etc to Gigabit, will I see an improvement?  I am not expecting gigabit transfer speeds but would be happy with 300 - 400 mb/s.

Any advice?
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CAT5 is not appropriate for gigabit. If you won't upgrade your cable to at least CAT5e you won't be able to use gigabit speeds and all you'll get will be 100 mbps even if all your ethernet adapters and switches are gigabit compliant. Then they will not be able to negotiate 1 gbps and fix the speed at 100 mbps.

So there will be no improvement if you insist not to replace your cabling. I'll suggest you to replace your cabling with CAt6 instead of CAT 5e though.

Cat 5 supports gigabit, all the interfaces that will use the lan will have to be gigabit interfaces that means that every computer must have a gigabit network card(these days most computers have buildin gigabit lan) and ur router and if you have a switch must support gigabit lan. Ur speed lan speed would increase to about 250-350.
There are couple of factor that are accountable when you talk about the throughput of the network, sometimes people upgrade the network but still don't get significant change in network speed. And the reasons could be starting from the physical level and up to the top Application level.

But in a typical multiuser network environment you normally get 25 - 30MB/sec.

Again there are many factors File Size, HDD speed, system and hardware performance etc.
KeremE said that cat5 doesnt support gigabite but fortunaly thats not true. Officiale cat5 doesnt but thats offical calculated over a distance of 100m for testing etc. But for Home use with short distances you can even use cat 3 for gigabite in theory. So cat5 can be used for gigabite for short distances like 10m its no problem.
are you going to plug in the machines individually to switches having gig port with each PC having gig NIC?

I am not sure how small your office network is, but if it involves 1+  switches then the uplink also need to be of fiber to support the gig transmission. 300-400mb/s transfer in lan is highly unlikely to get with minimal change. You need a major change.

Unless you are in real sos need, would suggest please put a break on to your plan which would be costly and would require a major overhaul at the cost of not $$wortrhy performance boost, if it's a small network.

Gigabit Ethernet can be run over Cat5 even though it's not supported.  If you have the budget and time, I'd suggest upgrading to Cat6 to eliminate the blame.  Every troubleshooting even will start with "You're only running Cat5, so ____ is caused by bad wiring."

Nothing about Cat6 runs are magically any different or better than Cat5 other than the components.

You may end up hitting some walls if some ports work and others don't.  No different that running high water pressure through old pipes.  It might work, it might not.  If you have a cable qualifier like a Fluke CableIQ it makes the process a lot easier.

I was able to test out a lot of office wiring.  Re-terminated around 10% of the ports and added a half-dozen new runs.  But, I didn't have to replace all of the wiring.  With space constraints, that was unfeasible.
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OK, My mistake, I found out my wiring is actually Cat5E.

Does this mean I can postpone re-wiring for a while and still get decent speeds?

as adnanj76: suggested, you will get probably less than that(<25Mb), you can well forget your target of 300- 400+mb/sec speed in lan.

What is the current speed you are getting and what's your practical expectation now after reading the suggestions?

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Well, networkin is not my forte, basically I woould be happy with twice the speed I get on my current 100 mbit lan.
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A further note -  there are TWO switches on the network
> wiring is actually Cat5E.
>Does this mean I can postpone re-wiring for a while and still get decent speeds?

Should be fine as long as the wiring is run and terminated properly.  Even brand-new Cat6 will not carry gigabit if it's not run right.  The label on the wire doesn't fix those problems.  If in doubt, rent/borrow a cable qualifier.

as per as my knowledge is concern the possibilities are---
1. CAT 5 support 10 mbps
2.CAT 5e Support 100 MBPS

if you change the routers/switches it may virtually show you 1 gbps (alongwith nic for 1gbps in your system) but  you will get actually 10 mbps or 100 mbps.

because your backbone of utp or the path through you data is travelling is either 10 mbps or 100 mbps... how it is possible to get an out put of 200-300 mbps where my input is either 10 mbps  or 100 mbps

note: any application running in network will not exceed 100 mbps....(as per my knowledge)

pls reply

^ I've maintained Gigabit Ethernet connections over a homemade Cat5 patch.  It's not to spec, but...

I've had "Cat6" labeled cable installed incorrectly that could maintain nothing better than single-pair POTS on 3 out of 4 pairs.

However, Cat5 and Cat5e can be used for 1000BASE-T, so not sure why you think 100Mbps is the limit.  1000BASE-TX required Cat6, but I don't know of anyone using it.  Assuming the O.P. here is not trying to use that technology.

Not all cable installations will work for Gigabit Ethernet, even ones labeled "Cat6".

The label on the cable doesn't "make" the connection good or bad.

Tester, qualifier, and certifier are the second-to-last step.  The last step is plugging in your equipment and seeing if it works.
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