- I recently finished a project for Cisco 9500 Series switches using StackWise virtual and ran into some scenarios where the StackWise virtual needed to be reconfigured or changed. I searched the Internet but didn't find much information on it.
- So, I am sharing some tips and tricks on StackWise Virtual so it could help anyone else in future.
- Please remember that my tests are solely based on Cisco 9500 Series switches, but for the most part, I believe that it should be the same on the other devices which support StackWise Virtual. Any feedback would be much appreciated to improve the article and maybe help other Network Engineers in future.
- For the most part, I relied on the following Cisco Article for the StackWise Virtual which has a great ton of information in it.https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9000/nb-06-cat-9k-stack-wp-cte-en.html
- Although the article helps with the overall design and initial configuration, I didn't find a lot of troubleshooting information or scenarios like changing the DAD or SVL link after the stack is online or what issues we could run into. So, this article is mainly focuses on different scenarios after the SVL is up and running.
- The most important thing to remember is that we need a DNA Advantage license for StackWise Virtual to work.
Scenario 1: Changing the Physical Dual Active Detection (DAD) links to SVL (StackWise VIrtual) links after the Stack is up.
- Below is a StackWise VIrtual between two 9500 Series switches along with a DAD link on Twe1/0/1& Twe2/0/1
- Let's say that for some reason we need to change the DAD to interface Twe1/0/2 & Twe2/0/2 from Twe1/0/1 & Twe 2/0/1 and change Twe1/0/1 & Twe2/0/1 to SVL links
- We will need a maintenance window as we will need to reboot the switches for the link to come up. But below is how I was able to achieve that.
- The interfaces were unplugged on Twe1/0/2 and Twe2/0/2
- # interface range TwentyFiveGigE1/0/2,TwentyFiveGigE2/0/2
# stackwise-virtual dual-active-detection
WARNING: All the extraneous configurations will be removed for TwentyFiveGigE1/0/2 on reboot.
INFO: Upon reboot, the config will be part of running config but not part of start up config.
WARNING: All the extraneous configurations will be removed for TwentyFiveGigE2/0/2 on reboot.
INFO: Upon reboot, the config will be part of running config but not part of start up config.
# end - Now, we will need to remove the Twe1/0/1 and Twe2/0/2 from DAD as the next step.
- Unfortunately, when I tried to configure the links directly as an SVL, there was no option for it. So, I had to remove the interfaces from DAD first and then convert it to SVL after the reboot.
- # interface range TwentyFiveGigE1/0/1,TwentyFiveGigE2/0/1
# no stackwise-virtual dual-active-detection
Stackwise Virtual Dual Active Detection Configuration for TwentyFiveGigE1/0/1 will be removed on reboot.
Stackwise Virtual Dual Active Detection Configuration for TwentyFiveGigE2/0/1 will be removed on reboot.
# end - Reload the Switch stack and once the HA is in sync, I used the following commands:
- # interface range TwentyFiveGigE1/0/1,TwentyFiveGigE2/0/1
- # stackwise-virtual link 1
- # end
- Reload the switch stack again to take the new configuration to take effect.
Scenario 2: Add a member interface in the SVL Port Channel without any cables connected between two switches.
- If we don't have a cable connected to the links we want to form an SVL on and an existing SVL already exists on other ports, then we can connect the same speed transceivers to the ports and add the interfaces into the SVL Port channel.
- I received the message "WARNING: SVL configuration will be ignored on lower (1G) speed." after adding the new link into the EtherChannel just as an information message that the new link speed should be negotiated at the same amount of speed as the other interfaces in SVL. In my case, I was using 10Gbps links.
- We don't need to get the cable connected in order to add the member links, but we just need the correct transceivers or SFPs into the interfaces that need to be part of the SVL.
- A reload will be needed for that port to be part of SVL.
Scenario 3: Upgrade the Link speed of SVL ports into an existing deployment.
- I also had a scenario where I needed to upgrade the link speed from 10Gbps SVL links to 25Gbps SVL links.
- For minimal downtime, we will still need to take the Secondary Switch office in the StackWise Virtual. So, shut down the Secondary 9K switches and upgrade the SFPs connectors with the new cables and boot up the Secondary switch after that.
- Although I haven't tried swapping the SFP modules to higher-speed modules while the whole stack was online, I think that we could run into issues with the speed mismatch in Port Channels, so this might not work.
Commands to confirm SVL link and DAD link:
#show redundancy
# show switch
#show redundancy states
#show stackwise-virtual bandwidth <--- This command will show the SVL Bandwidth
#show stackwise-virtual dual-active-detection <----This command will show the DAD Link Information
#show stackwise-virtual link <-- This will show SVL Link information. I usually look for U (Up) in Link-Status and R(Ready) in Protocol status
#show stackwise-virtual neighbors
#show stackwise-virtual switch <Number>
# show platform software fed switch 1 qos qsb interface <SVL interface name>
Any suggestions or feedback are welcome since I have just put in the information that I ran into during my deployment, so maybe there is a scenario someone ran into that might help others with this post.