Redundancy using 4108gl core

[Pete UK]

Hi,
We have a single 4108gl chassis (CORE1) with GB modules. The ports are either connected to servers or 2626 edge switches.

All desktops are connected to the edge switches.

We would like to create extra redundancy by adding another 4108gl chassis (CORE2).

Each edge switch would have a copper connection to CORE1 and a second copper connection to CORE2.
Each server would have NIC1 connected to CORE1 and NIC2 connected to CORE2.

By doing so, if one of the cores fails (or needs to be powered down), the other core will take over connecting the servers and edge switches.

My questions are:
Would simple spanning tree work in this scenario?
Would I need a trunk link between the cores?
Is there a better (more elegant!) way of achieving Core redundancy?

I realise that one of the cores will effectively be sitting idle, but that is not a problem - we have the budget available!

Thanks in advance
Pete

[Mohieddin Kharnoub]

Hi

In regards your questions:
- Would simple spanning tree work in this scenario?
Yes. (unfortunately the 4100 doesn;t support MSTP but you can use the RSTP).

- Would I need a trunk link between the cores?
You should plan for the RSTP very well, so one 4100 playing as a Root, and the other as a Backup, and say 2Gig uplinks between them for better performance if you have some servers or ... connected to both cores.

-Is there a better (more elegant!) way of achieving Core redundancy?
Yes
by replacing the 4100 with 5400, so you can have L3 redudancy as well as better L2 redudancy.

Explanation:

Now with this scenario you can have L2 redudancy based on the old RSTP protocol.

With the 5400, you can improve this L2 redudancy with MSTP which will load balance between Vlans, so you don;t have a blocked port (and you've paid for the cable already but with RSTP its just blocked and doing nothing).

Also
You can get L3 redudancy - VRRP and that need a license.

If your budget can;t afford 2 of 5400, you can have 2 of the 5300 which support L3 redundancy - XRRP and also MSTP.

Good Luck !!!

[Jonathan Axford]

I would definately agree!

If you have the budget, it would make sense even just to get one 5400/5300 as a starting point, with a view to getting a second one when ever you can.

The 4108 isn't a brilliant switch in my opinion and if there is any chance of replacing it then i would go for it!

Cheers

Jonboy

[Pete UK]

Thanks for your help.
I'll have a look at the better switches, and see if I can improve the design.

Cheers