Confused between 2 topologies

[Abuzar]

Hi

we have 3 cisco Layer3 Switches & a Router, and we are confused between 2 topologies, we need your help to select the best one.

so is it good to connect all switches to router only or connect them togather instead of router to route all traffics between switches to provide  redundancy?

i have attached the topologies.

[Joseph W. Doherty]

You might find either topology a bit difficult to get working with a 2911, depending on your VLAN/network scheme.  Built-in 2911 are routed ports, and by default you cannot have more than one logical interface on the same network.

Assuming all your devices are within the same network, physically, I would recommend having some redundancy between your devices.  I.e. topology 1 doesn't offer any L2 redundancy.  Also, it doesn't need to be a full mesh as your topology 2 has, a ring topology would suffice, but you can use the full mesh if you desire.  Assuming you do have a multi-path L2 topology, you'll should determine which links will normally be unblocked.

[Abuzar]

Thank you for your answer.

First I want to confirm that:

- My router is 2921 and I have additional port in it, and all my switches are layer 3.

- I think that my second topolgy is good if it can be done (with STP of course), and I want you opinion in that.

My porpuse is to have speed and redundancy in case my router or one of my switches went down.

For now all traffic must go throught my router, in addition to redundancy I think it makes my network traffic slower.

My questions here is:

- Will topology2 give me redundancy in case my router or one switch go down, i.e. if my router go down will the computers still connected ?

- Are there better solution in terms of redundancy and speed?

[devils_advocate]

Are all the devices in the same physical location (i.e. not across WAN links)?

Personally I would look at making the 24 port Cisco the 'Core/Distribution' switch and use this for your InterVlan routing.

I would then hang both of your 48 port Access switches off this.

Unless the router needs to have the other switches plugged into it, then there is little benefit in doing so, especially considering the router will likely only have L3 routed ports. 

Do all your internet based NAT stuff on the Router and then use Static/Dynamic routing between the Layer 3 switch and the router.

My 2p anyway. 

As Joseph says, there is no redundancy so this could be a concern if you ever lose the Layer 3 switch. I would always have redundancy at the Core/Dist layer at the very least and preferably at the router level also.

Thanks

[Abuzar]

Thank you for your answer.

Yes, they are in the same physical location for now.

Can you please explain to me why making my 24 port switch the 'Core/Distribution' switch better than topology2 ?

Are you mean that there is no way to make the switches connect to each other without a router or 'Core/Distribution' switch ?

And please read my previous replay.

[Abuzar]

Any suggestions?