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Five Story Building Fiber Link Speeds

I am designing a new model and am really grappling with the fiber uplink speeds.  I am trying to build a network resilent enough to support data for the next ten years.  I am trying to decide if I need a 10 gig fiber uplink to my data center on the third floor of the building from each of the adjacent floors.  I am planning on running a 48 port gigabit switch on each floor, and at the moment without VOIP.  But I'm trying to peer into my crystal ball for years down the road to see what my requirements will be.  Currently we are a 10/100 based LAN with all the normal windows domain things, file shares, exchange, internet, etc.  I could also concatenante some 1 gig fiber links, say 4 per floor, to get to almost half the bandwidth but with multiple fiber strands.

Either way I was just hoping for some feedback.  There are advantages to each, I'm just worried as my switches begin to max out the ports, and the computers and network start utilizing the gigabit bandwidth more that my uplinks will begin to be the bottleneck, not today or tomorow, but a few years down the road.  Am I crazy?  Any help would be greatly appreciated, or a link to a thread that has already addressed this issue.



Network Admin

The Blood Center

Hall of Fame Master

Hello Jason,

to build a network that can grow for years you really would need the crystal ball.

However, the answer is in the current applications and possible introductions of new services.

I guess you work in the health sector that is taken as example for the need of transferring very high resolution images ( exam results on patients for example), the possible need for video conferencing may be again with high speeds.

The traffic patterns of these applications can be quite different: file transfer may cause high peaks of traffic, video conferencing like streaming uses something similar to a high but constant bit rate.

There are network design guides at

there is an healthcare section here:

Clearly you should use 10G uplinks for giving you space to grow. Also for each floor you should consider for example stackable switches with 10GE uplinks. the stack cable in 3750 can be 32 Gbps or 64 Gbps of speed and it is a sort of ring.

When you need to add users you can add a switch with 48 ports to the current switch to build a stack, eventually moving second 10GE uplink to second chassis.

This can be a good solution for the floors.

on the distribution layer you should have C6500 with sup720 and one C6708 10GE linecard, two linecards of this type if you want to reduce oversubscription. (the linecard can communicate at 40 Gbps with switching fabric)

You can consider to use the same two switches also for the data center or to deploy a second pair of C6500 (budget can be a problem)

Hope to help




  Thanks a lot for the response.  I'll check out the links as well.  I think I've decided to go 10g for the heavy user floors, and 1g for some other less used floors, with the ability to upgrade to 10g links if they outgrow the uplink.

thanks again,


Hall of Fame Community Legend

In addition to Giuseppe's post, the new 2960S supports 10Gb SFP+ interface plus it's stackable.

Your next question should be what flavour of fibre should you use:  Single Mode or Multi-Mode.  Owing to the distance, multi-mode is the way to go.  But there has been unsubstantiated murmurs that installing Single Mode for ultra-high speed (>1Gb) is better.  I have only seen a very outdated document to support this so I'm very skeptical.

You say you are building a resilient data centre.  How important is it?  Clients who deem the data that flows in and out of their data centre to be important implement redundant data centres with redundant power.  I would understand if cost is a factor so I'd consider redundant power. 


Now that I have the design down, I need to find the cisco equipment that we can afford and will support my requirements.  I've got 3 vendors working on quotes right now.  Hopefully I will get something that is affordable for us, we are a non profit, so we are usually pinching poor honest abes head off.

As far as the fiber is concerned, I have a local company that will probably pull the fiber, and I will defer to them for their recommendation.  They have a lot more experience then I.

We are lucky when it comes to power, we actually have an industrial ups that supports our labs, and has been incredibly reliable, I cant remember the model off the top of my head, but it literally takes up an entire room.  I can honestly say we have the best power system I have seen in my 10+ years of doing IT work.  I'm hoping with the right lan infastructure design coupled with the robust power and AC our data center at our main facility will be rock solid.  After the move I'm going to refocus on replicating data to our secondary location.

Thanks for the feedback


Hall of Fame Community Legend

I have no idea about the workmanship of the cablers over at the other side of the world, but we have our fair share of "shonky" deliveries here.  Make sure the cablers provide you with a Optical TDR result.  One of the give-aways that the results were tampered or doctored is the length.  Each termination pair should have different lengths.  If two or more pairs have the same lengths then you should ask questions.

Hope this helps.  Don't forget to rate useful posts.  Thanks.


"Owing to the distance, multi-mode is the way to go.  But there has been unsubstantiated murmurs that installing Single Mode for ultra-high speed (>1Gb) is better.  I have only seen a very outdated document to support this so I'm very skeptical."

for 1G

Mostly Multimode can give you distance of 300-500m. Enough distance for multistory building

For 10G (whic the poster wants to use)

OM1&OM2 fiber give you 30-100m. Not enough distance i suppose

OM3 can have distance of 300m . Enough distance for few story building

I hope you will have 100G  in few years, there is new version of Multimode fiber OM4 for that kind of speed. As OM3 will not be sufficient for those speed

Keep aside the cost of inetrface /fiber for a minute

If you use the simplest (cheapest) of SMF is going to work whether it is the tallest building in the world or you want to use for 100G.

I hope you can decide whether that document is outdated or not?


It’s not easy to comment on how your technology strategy for the next 10 years should be since I do not know anything about what the organization is doing or which applications we can expect on the network.

The easy answer will be to use the highest bandwidths and best switches you can get but this comes with a price that might give you a bad ROI the next 5 years. So what you can do is to look in to the future and predict if video, cloud computing, or any other high bandwidth applications will be present in this infrastructure. And the answer to that should be yes – sure… etc. But when is also a key question. So for your design you should plan ahead and see what you need now and if there is better to upgrade later. Do you then want to do a forklift upgrade and replace everything, or do you want to replace some components / interfaces to get higher bandwidth? You can address now that you have a technology strategy that points out the direction for the next 10 years, and you have a plan on how to build this new network now according to this strategy. You should address that i.e. after 5 years you need to do the next step and invest to upgrade the network according to the strategy to gain higher bandwidth, better SLA or any other upgrade that is critical for the business.

Even if you go for 10Gbps now it might not be what you need in the future. And even if you have a 10 year scope for your strategy you should occasionally do a sanity check and patch up your strategy to meet the requirements from the organization you are going to support, and to be aligned with the technology development.


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