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Designing a new network and looking to use 2920 switch series.

Occasional Visitor

Designing a new network and looking to use 2920 switch series.


our factory has been relocated recently and we are buidling our new network from scratch.

right now we are installing passive equipments. 

we have a 4 story building where emploees are located in which we have 3 floors that each will have 15-17 workstation + 3-4 IPcams and 1-2  wireless access points and 41 workstations in lowest floor next to the server room.

the R&D department consist of 24 workstations (located in lowest and part of that 41 workstations) works with Autocad Vault and uses a NAS device with 4x GbE interfaces. ( we might later upgrade the NAS to a model that has 10GbE interfaces.), they are the only bandwidth hungry people we have in the company.

also 2 Dell edgepower with 10GbE interface but they are currently working with 2x GbE.

we will have 25-30 IPcams later but they will be connected to the network with smaller switches across the factory.

so since we need a GbE infrastructure, i came across the 2920 series.

there is one thing to consider that we want copper trunks (10GbE) for the switches (as the factory owner had difficulty with fiber before and now he doesnt approve using fiber as trunk.)

what would you recommend ? should i go with 2920 series and if so, which models ? 


thank you for your time reading this.

Honored Contributor

Re: Designing a new network and looking to use 2920 switch series.

I missed the total numbers of ports required (10GbE, 1GE) to connect all your hosts. A clear Network Topology (physical and logical) is really mandatory to understand and verify your actual (and future) networking requirements.

Think that up to 4 (four) Aruba 2920 Switches can be backplane stacked togheter using specific 2 ports Stacking Modules (J9733A) and related Stacking Cables (J9734A, J9735A and J9736A) - maximum 3 meters long (with J9736A) each one - in a Ring (preferred) [*] or Chain [**] topology.

So if you go - let me say - with 48 ports Aruba 2920 models stacked togheter you will end up with a "Logical Switch" made up of:

  • 48 1GE ports/unit x 4 units = total of 192 1GE ports,
  • 2 rear Slots for 10G Expansion Modules/unit x 4 units = total mix of up to 8 Expansion Modules, each one, providing two 10GbE SFP+ ports (J9731A) or two 10GBASE-T ports (J9732A) permitting a grand total of up to 16 10GbE ports or 10GBASE-T ports (or any combination of them up to the maximum of 16 ports)

at maximum and for the entire Stack.

[*] 4 Switches Ring Topology: required 4 Stacking Modules and 4 Stacking cables.

[**] 4 Switches Ring Topology: required 4 Stacking Modules and 3 Stacking cables.

Other interesting Switches can be:

  • Aruba 5406R zl2 or Aruba 5412R zl2 equipped with v3 zl2 Modules and running KB.16.01.xxxx System Software or newer (to benefit from VSF Virtual Switching Framework).
  • very new Aruba 2930F (read here).

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Occasional Visitor

Re: Designing a new network and looking to use 2920 switch series.

Please excuse my poor explaination. here it goes :

first 3 floors are just the same : 

15-17 workstations, 4 IPcams (PoE), 2 wireless AP (PoE)

the lowest floor will have 41 workstations that i think its better to get a non-PoE switch for that (to reduce the cost) and since the NVR already has 8 ethernet interface and the IPcams are 7 in that floor, should be fine. there will be 3 wireless APs with PoE injectors.

in server room we have 2 server with dual GbE interfaces (4ports in total) but we might use the 10GbE interface on them if we find a low cost and small 10GbE switch and there we can upgrade our NAS (currently 4x GbE) with a model that has 10GbE.

so if i go with 3x J9727A for upper floors and one J9728A for lowest floor and use 4x J97312A (2-port 10GBASE-T module), what would i need as an access/dist switch cosidering i want 2 trunk on each switch for redundency. 

thank you for your help.


P.S. i looked at 2930F, they all only have SFP/SFP+ and as i mentioned before we want copper trunk.


Honored Contributor

Re: Designing a new network and looking to use 2920 switch series.

Again: you need to clarify to yourself if you're speaking about a "star" topology (physical) in which you are going to have a core Switch to which all floor Switches (those with a edge and access role at the same time) are connected using 10GBase-T copper uplinks or not.

A drawing (of your intended network topology/logic diagram) would help you and maybe others to guide you better.

Uplinks between edge and core Switches should be configured as Trunks made through LAG(s) set with LACP, LAG(s) should be created aggregating 2 x 10GBase-T ports if you don't want to create them using simple 1G ports. In both cases Uplinks so done are for redudancy and resiliency too.

Setting Uplinks in that way will force you to have a core Switch able to terminate all Trunks you have in your "star" topology: if every floor (excluding the floor 0) has a Switch equipped with 2 x 10GBase-T ports Expansion Module then the core Switch is going to need the total of 3 x 2 x 10GBase-T 6 ports (grouped in three separate LAG(s))...such scenario, with just a single Aruba 2920 on the core side, isn't possible (the Aruba 2920 is limited to 4 10GBase-T ports provided by 2 Expansion Modules).

The above is the requirement to manage Trunks doesn't include your DELL Servers on floor 0 nor your near future 10GBase-T based NAS.

If you don't care about redudancy and resiliency of your Uplinks between the core Switch and the edge Switches you can think to use just 1 port (of a pair) of 10GBase-T Expansion limiting the 10GBase-T ports usage to 3 x 1 x 10GBase-T on the edge side and 3 x 1 x 10GBase-T on the core side...again you have a problem (ports bottleneck) because then you haven't room to serve your DELL Servers with 10GbE ports (now and in future) since on the core you were left with just 1 10GBase-T free port (2 Expansion Modules = 4 10GBASE-T ports).

Addition: you can always create LAG made of two or more 1G ports to save on 10GBase-T ports...but this move the problem from having a sufficient number of 10GBase-T ports to having a sufficient number of 1GB ports (to use as aggregated uplinks) between the core and the floors. Maybe cheaper but you always need free ports to dedicate for aggregated trunking.

At least if you don't start considering to use VSF on your core side: two Aruba 2920 in Stacking...this will double your 1G/10GBase-T ports availability to your floor 0 hosts and for your Uplinks to your floors.

All that said not considering that your 24 ports edge Switches and your (single) 48 ports core Switch are going to be almost full at very beginning of your network setup (imagine if you add Network Printers or other network devices):

On floor 1, 2 and 3: with 17 Workstations + 4 IP Cameras + 2 Wireless APs per floor ...a 24 ports Switch isn't a good starting choice.

On floor 0: with 41 Workstations + 4 Wireless APs AND Servers to be served ...a single  48 ports Switch isn't a good starting choice.You're at risk of understimate your topology least if you're not considering other Hardware you've not included in your BoM.

Addition: not considering that you should also use VLAN(s) and take care of them when deploying your solution.

Just my opinion.

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