When to switch from flat to routed?

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iceisfun

Member
Jul 19, 2014
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How big is too big for people setting up flat networks?

I'm getting to the point where I think there are a lot of spanning tree events and now I've had a situation with a Ubiquiti ES-16-XG 10gb switch that failed to block a spanning tree loop causing a forwarding loop, it took me a little bit track down the root cause.

This has only happened to me once, however I consider chopping up this network into different routed l2 segments. So how big is too big before chopping up one of these networks?
 

Evan

Well-Known Member
Jan 6, 2016
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For most people it’s less the size and more the security requirements.

The biggest I have seen still working well is 4 class C subnet and probably containing about 600-700 end points.
Probably not advised but it worked actually without any issues.
(Cisco catalyst 4500 chassis as core/distribution and server access and something else catalyst as access) was back in the 1G days and not demanding users in terms of traffic just regular office.
 

klui

Well-Known Member
Feb 3, 2019
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I'm getting to the point where I think there are a lot of spanning tree events and now I've had a situation with a Ubiquiti ES-16-XG 10gb switch that failed to block a spanning tree loop causing a forwarding loop, it took me a little bit track down the root cause.
Something is wrong if you're getting all these spanning tree events.

Look at the first 2 hits for "spanning tree events" and investigate further.
 

Terry Wallace

PsyOps SysOp
Aug 13, 2018
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I'd have to agree with klui. A flat network doesn't get spanning tree events unless your either (A plugging a cable from it back into itself somewhere else) or (B configuring smart switches with routes or have smart switches detecting routes and directing traffic)
How many machines are in your network ?
 

Rand__

Well-Known Member
Mar 6, 2014
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Or C - have some technical issues causing port flapping or similar thus triggering stp recalulation
 

iceisfun

Member
Jul 19, 2014
31
4
8
I'd have to agree with klui. A flat network doesn't get spanning tree events unless your either (A plugging a cable from it back into itself somewhere else) or (B configuring smart switches with routes or have smart switches detecting routes and directing traffic)
How many machines are in your network ?
I've exaggerated the spanning tree event frequency, it just worries me that the network has become too large.