Creating IRF with 3 switches on daisy chain, or...

[marti28]

Hello,

I have a doubt regarding IRF configuration.

My scenario is the following:

We have a stack of 2 5700's switches in daisy chain topology, we plan to change this switches by creating a stack of 3, disconnect one of the switches and again, add the last switch. Then, we will replace all 2 switches by 2 brand-new switches, same model and firmware.

Therefore, I have identified 2 possible solution approaches:
1. To create the IRF stack of 3 switches with daisy chain topology, simply by adding the third switch. My doubt here would be how to physically connect this third switch with the other 2 switches. Finnally, I would just add the last switch creating a 3 switches stack and finnally disconnecting one of this, so the outcome is a stack of 2 switches in daisy chain topology.

2. To change the current topology of the switches to ring topology, and add the switches inside this ring topology, which seems better in terms of throughput and reliability. My doubt here would be if changing the topology from daisy chain to ring topology interrupts the service in ANY means? In order to avoid service interruption (if there is any), do we need to physically modify the connections between the switches?

Thanks for the help.

Regards.

[akg7 · Accepted solution]

Hi,

Please find my response:

Suppose if you are connecting 3rd switch to the topology as Daisy chain and starting replacing then you can replace switch 1 first but the probelm will occur when you will replace switch 2 because there would be no conncetivity between switch 1 switch 3.

Suppose you are implementing daisy chain as per the attachment:

Renumber the 3rd switch

irf member 1 renumber 3

save and reboot the 3rd switch.

Then you need below configuration:
Switch1:
++++++++

irf-port 1/1
port group interface Ten-GigabitEthernet1/0/49
#
save
irf-port-configuration active

Switch 2:
+++++++++

irf-port 2/1
port group interface Ten-GigabitEthernet2/0/49
#
irf-port 2/2
port group interface Ten-GigabitEthernet2/0/50
#
save
irf-port-configuration active

Switch 3:
+++++++++

irf-port 3/2
port group interface Ten-GigabitEthernet3/0/50
#
save
irf-port-configuration active

And if you want to change it to Ring topology then you need to connect Switch 3 interface tengig3/0/49 to Switch 1 interface tengig 1/0/50 and below configuration required (Pls refer attached diagram).
But pls make sure that for IRF ring we need more than 2 switches.
As I tested in LAB, in ring you can easily replace switch 1 & 2 one by one.

Switch 1:
+++++++++
irf-port 1/2
port group interface Ten-GigabitEthernet1/0/50
#
save
irf-port-configuration active

Switch 3:
+++++++++

irf-port 3/1
port group interface Ten-GigabitEthernet3/0/49
#
save
irf-port-configuration active

Thanks!