We have 7 Dlink DGS-3120 48 ports Gig switches stacking together and all ports are being used. Each switch represents a single segment of our working area. it is working well without any issue.

My question is that there is a 5-4-3 rule for network topology, but looks like our switch stack got nothing to do with this rule....? or newer technology has overcame the 5-4-3 limitation?

any idea why?

another question is how many switches can be connected in series?


The 5-4-3 rule is largely outdated: A switched Ethernet network should be exempt from the 5-4-3 rule because each switch has a buffer to temporarily store data and all nodes can access a switched Ethernet LAN simultaneously. More on the 5-4-3 rule here.

  • Thanks for the answer on the first question. Looks like it is an old rule to to consider. how about 2nd question: how many switches can be connected in series? – Root Loop May 7 '14 at 16:02
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    Honestly, as long as you structure your network correctly, there are no real physical limits you can run in to anymore. However you should take into account the routing complexity if you create to large a network. Anything over 50 switches is problematic. But you're unlikely to reach too great a number of switches in any small business network. – Reaces May 7 '14 at 16:31

I asked a CCIE the same question, about how many switches can you have in series. He said no real limit, you could string a hundred together end-to-end, for example. There would be some limit depending on the timeouts used by your network stack, but that would vary according to the user.

  • Bandwidth between switches starts becoming a problem when you've got a server on one end and lots of clients accessing it on the other end of a serial chain. Some high end switches have high speed backplanes but the cheap ones use your regular switch ports to cascade the switches. – Matt May 7 '14 at 20:53

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