Connecting 2 Switches problem (Cable length?)

[Shorty]

Hi All,

 

We have two buildings about 80m apart. A few years ago I got a Cat5e cable laid to connect the two together with a switch at each end and all was workign fine.

I have just upgraded my old switches to Netgear GS524uk 24 port Pro Safe switches. Now this is were the problem starts, I cannot get the two to connect i.e show any lights when I connect them directly but... when I add a 5 port switch into the mix I can get a connection. I have had the two new switches side by side and know they work.

 

I am wondering if its the cable length I have just used a trundle wheel to follow the exact path of the cable and it actually comes to about 120m which I know is more than ethernet should be connected. Do you think this is the problem ? 100mb is fine but at gigabit speeds it just cant cope ?

 

The whole point in this excercise was to allow gigabit speeds between the buildings :-(

 

Anyone got any ideas neither of these switches have fibre connectors and I dont fancy trying to relay a new cable.

 

Are there any devices that will extend the distance limitation ?

 

Any help will be greatfully recieved.

 

Cheers

 

Shorty

[plexer]

I think you've answered your own question as to why it doesn't work.

 

Ben

[Michael]

The limit for 100Mbps is also 100m so you're lucky to get any connection at all.

 

I see several solutions to this problem. Purchase another gigabit switch and try and place it in the middle (if possible) of the 100m distance. If this isn't possible then you may need to look at fibre and convert the connection back into copper at each end. Alternatively re-route the cable so it is less than 100m, but I would of thought you'd of used the shortest distance already.

[MichealJones]

If these switches art in different buildings, then you shouldnt be using copper to join them anyway in case of electrical faults in either of the buildings, it is against building regualations also to join them with copper.

 

Fibre will give you a better service over this distance and more reliability too, otherwise you switches might might perform as well as they could do.

 

Hope this helps.

 

Micheal Jones.

[plexer]

it is against building regualations also to join them with copper.

 

Is it? can you point me to somewhere that states this?

 

Ben

[Oops_my_bad]

it is against building regualations also to join them with copper.

 

Interesting - whilst our buildings are linked by fibre, there is one linked with a copper for the telephone to the PBX- how do you get round that one?

[MichealJones]

We had a building servey done by a local firm who work for the LEA, everything was fine apart from the fact the new PE offices were connected with a standard copper network cable. This had to be changed for a fibre to satisfy the 'regualtion' i menetioned before... I was simply stating what we had done here.

Maybe it is not a national thing? I know telephones are copper, and they go through a 'grounding' box. All this is something to do with lighting strikes and possibly killing all your switches if one remote building was struck and the rest were directly connected with a copper cable.

 

Ill see if there is anything on the companies website to back up what they told us

 

Micheal.

[Shorty]

Hi Guys,

 

Thanks for the replies. The thing that is confusing is that I have just put a small 5 port Gigabit switch on the other end of th ecable and this is connecting and registering as connected and at Gigabit speeds ? Bizarre.

 

I am going to go and have a look to see if I can shorten the cable any and just replace each RJ45 to see if that helps otherwise i will have to look at adding a switch mid route.

 

Cheers

 

Shorty

[Shorty]

Yeah success \0/

 

I manged to get it working, I crawled around in the roof space of one of the buildings and found about 10m of slack !!! I also replaced each end fitting. At first I got a pulsing connection so I did a bit more investigating and found another 5m of slack getting rid of that finally gave me a solid connection. I must be right on the limit for gigabit.

 

Anyway fingers crossed this will stay up ;-)

[danrhodes]

Hi,

 

I would just change to Fibre if I was you, your setting yourself up for problems going with copper building to building even if it is Gigabit. You should go Fibre 10GBps??

 

Dan

[brokitt]

The regulation thats this falls under is electrical and is due the Possible Earth differential between building you can find requirements and explanation in electical guidline link below should give you a bit more info.

 

Electrical Installation Guide - Google Book Search

[Zimmer]

We had a similar issue a couple of years back...

 

We had six workstations in the college's gym, one a register PC and five other staff workstations. The gym is on the other side of a small adopted road at the rear of the campus with an electrical supply independent of the colleges on-site substation.

 

At the time the workstations interconnected using a 3Com 4228G switch, in turn uplinking to the main campus network using SOHO D-Link wireless bridges and external high gain antennas. As time passed by we soon realised that the speed and reliability of the WiFi link (not to mention the potential security risks too!) was not suitable for carrying domain traffic. Also, having roaming profiles and folder redirection enabled didn't help with logon times for those using the gym workstations.

 

We ended up looking into throwing a Cat5e cable over from one building to the gym (attached to a tether cable) and we soon discovered the issues surrounding buildings with different power sources and the building regulations preventing this solution.

 

As mentioned by the peeps above the best solution would be to go fibre, that's exactly what we did and now the gym is uplinked at a healthy 1Gb/s to the campus backbone.

 

If I remember correctly the cost of the fibre installation didn't break the bank, the only real cost was that of the fibre modules for the switching kit.