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Jaroslav LatalFlag for Czechia

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ethernet cat5e lenght 80m

Dear experts,

I need to lay ethernet 5e cable in college building. The building has 10 floors and I need to lay 1 cable for each floor, because each floor is connected to specific Mikrotik router port.

The problem is that from 10th floor to server room is it about 80 to 100 meters. Each floor is limited to 17mbps, so I don't need higher speed.

Do you have some real experience or a link to some trusted info about it?


Regards,
Jarda
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Antzs
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The longer the cable does not actually relate to the speed in which data travels.  The max 100m Ethernet cable length is just a TIA standard.  For any cable longer than 100m an active device is required in between the cables to boost up the signal to prevent signal drops.

But, I have used cable longer than 100m, in my environment( I think it was 250-300m) and it worked just fine.  That said, I still prefer to follow the recommended standard unless the situation does not gives you the choice to follow the standard.
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Dr. Klahn

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So I will pull Datacom Cat5e cable and will see what happen. In the worst case I will later buy some cheap switch and put it somewhere between.

There is about 20 devices on each floor, 2 buildings with 10 floors each. About 400 active devices (students) shares 300mbps internet connectivity. As a router, I used 24 port Mikrotik for $160. Poor students... But the budget is not so high.

Do you agree with this solution or I will beat my head against the wall in few days?


Kind regards,
Jarda
I typed answer for cables only. For design consideration more details should be provided (including basic topology and list of devices in use).

But from what I read, why wait for few days? Start beat your head against the wall right now.
😊

For start place 2 fibers between buildings (if not already present), at least that's what I would do (Dr.Klahn also suggested it).
Those buildings are very close together (20 meters). They will not pay fibers or some sophisticated solution, there is no budget for it.

Now there is one router, one cable to each building. On a 1st floor is 100mbps switch, from this switch it's connected to another switch on 2nd floor and so on. Simple cascade of 10 switches in each building. When one switch fails, the rest of building doesn't work.

Should I spend $1000 for a "small upgrade" described above or let it as is.


Thanks,
Jarda
Thanks a lot for help!
You know limitations, those are just best practice sugestions.
Typical design is L3 switch per building.

Where you will most likely have problem is natting for 400 hosts (but again don't know complete design). NAT uses router's CPU for work and is not offloaded to a ASIC. So that can become a huge problem, since it can effectively kill your router.