Hello,
I’m opening this thread today because we are planning to upgrade some devices in our network.
We are planning to update two 3750 stacks and two Nexus core switches.
The goal of this case is to have your opinions and advice about the possible impacts of those updates.
Here is the current network topology :
1 - The first step is to upgrade those 3750 stacks, beginning witch stack number 1.
About the wan connections, firewalls have rules configured as follow : If any of the links with WAN or 3750 stacks fails, failover is activated and standby firewall become active.
We expect a short network interruption (time during HA balance between firewalls) since updating 3750 stacks require a reload.
This is the first impact spotted, but which should be pretty quick (or even almost transparent depending of FW HA balance duration) as traffic will still flow through Nexus 1 via 3750 stack 2.
When updating 3750 stack 2, we expect no impact.
2 – The second step will be to update the nexus core switches. Firmwares have been uploaded, and the “show install all impact” issued.
The nexus core switches update will be disruptive since L3 features are enabled, so we also expect some impacts.
We will first update the nexus core switch 1 (and by extension the FEX 1 connected).
When the Nexus core 1 switch will reload (after the update), we expect short network interruptions since they have HSRP group configured.
The Nexus core 2 will transit from stand-by to active during this reload, and we expect traffic flowing through the 3750 stack 1
The Nexus core 2 switch and FEX2 updates should not impact us at all.
Beside of the HSRP state changes during Nexus reload, I did not spot any other impacts mainly thanks to the vPCs.
Could you please take a look at this scenario and warn me of any unidentified potential issues please ?
Thanks for helping !
Kind regards,
