Stacking 2950T-48-SI

[tijojose]

I am having 6 2950T-48-SI switches. These switches have 2 1000BaseT ports instead of GBIC slots. Will I be able to stack them like other 2950s. If so , how?

Regards,

Tijo

[don.orlik]

Tijo,

First of all I would recommend that you don't stack 6 2950T's (48 Ports) in one stack. It is dependant on your environment but I would recommend that you use some form of aggregation switch such as a WS-C3550-12T. If you use this type of device as your core/distribution box you would be able to create a highly available, highly scalable network. If you can't or prefer not to use some form of device as the 3550 then you would stack these devices just as you would 2950G's with Gigastack modules. The difference is that you are not using the Gigastack Loop Detection feature but instead you are using regular spanning-tree.

Here is what the device setup would look like. Connect the switches together using CAT6 cross-over cables.

A switch G0/1 connects to B switch G0/2

B switch G0/1 connects to C swtich G0/2

C switch G0/1 connects to D switch G0/2

D switch G0/1 connects to E swtich G0/2

E switch G0/1 connects to F switch G0/2

F switch G0/1 connects to A switch G0/2

This will give you a stack of switches. Configure the A switch to be the spanning-tree root. This will allow the D switch to block one of its uplinks (most likely the one to the C switch). This will ensure that both links to the A switch are being utilized.

You can still run CMS to manage the stack of devices.

Hope this helps.

Don

[tijojose]

I will have 2 3750G-24T-E switches for redundency as a collapsed core-distribution layer. They will be cross connected for redundency. Each access layer switch will have 2 uplinks - one to each 3750. Also I will have other unmanaged d-link switches connected on these core switches.

Do you suggest aggregating all the switches to 3750G-24T-E rather than stacking them? I intent to use 2950Ts for VoIP and unmanaged d-link for data traffic.

Regards,

Tijo

[don.orlik]

Tijo,

Ok. Here is what I propose for your environment based on what you have provided here. Since you are planning to create a VoIP network, I would recommend that you create the following network.

The two 3750G-24T are good for your collapsed core-distribution layer. If this is all one closet (which I assume it is), I would create the setup in the visio diagram attached.

I would not use the d-link switches unless you have a port density problem. I would create two VLAN's (one for data and one for voice). Connect all the PCs' to the phones (if you can), and use the aux/voice vlan feature on the Cisco Switches. Configure the two 3750's as Layer 3 devices. In addition configure the 3750's for redundancy using HSRP. Configure the primary 3750 as the primary for Data (both spanning-tree root and HSRP) and configure the secondary 3750 as the primary for voice (both spanning-tree and HSRP).

Now we start talking about Quality of Service on the LAN. Configure the phones to set the IP Presendence bit to 5 (this is standard on Cisco and Nortel Phones, on Avaya Phones the TOS bit is set to 6). Configure the swtiches to Trust the Class of Service.

I think this should get you started in the right direction. VoIP is very sensitive to Delay, Jitter and Latency. Ensure that you create the ideal network for both Voice and Data will giving priority to the Voice Traffic. For the size of network that you are creating, there is no need to create a seperate Voice and Data Network. A converged network if configured correctly should cause you no issues.

Hope this helps..