In this post, I will show you how to configure StackWise Virtual on a pair of Cisco Catalyst 9606R switches.
Cisco StackWise Virtual is a switch virtualization technology that combines two switches into one virtual switch. StackWise Virtual simplifies network management since you can manage one stack of switches instead of each switch independently.
In other words, through Cisco StackWise Virtual, two physical switches can be managed as a single logical virtual switch.
In addition to giving you the commands to configure StackWise Virtual on the 9606R switches, I will show you how to select what ports to use on the StackWise Virtual Link (SVL) and potentially for the uplink to a Layer 3 Aggregation core.
StackWise Virtual Sample Configuration
The section below provides the StackWise Virtual commands to be applied on Catalyst 9606R Switch 1.
switch priority 15 config terminal stackwise-virtual domain 10 end interface range hu1/0/39,hu1/0/47,hu2/0/39,hu2/0/47 enable ! turn on 100 Gbps support stackwise-virtual link 1 end write mem reload
The following StackWise Virtual commands need to be applied on Catalyst 9606R Switch 2.
switch renumber 2 ! switch ID will become switch 2 after reload switch priority 14 ! Optional - default is 1 config terminal stackwise-virtual domain 10 end interface range hu1/0/39,hu1/0/47,hu2/0/39,hu2/0/47 enable ! turn on 100 Gbps support stackwise-virtual link 1 end wr reload
The above CLI configuration assumes the following hardware on the Catalyst 9606R pair of switches.
- Slot 1: C9600-LC-24C
- Slot 2: C9600-LC-24C
- Slot 3: C9600-SUP-1
- Slot 4: C9600-SUP-1
- Slot 5: C9600-LC-48YL
- Slot 6: empty
I hear you asking: why did Rio use hu1/0/39, hu1/0/47, hu2/0/39, and hu2/0/47 to create the StackWise Virtual Link? Because I wanted to include in the StackWise Virtual Link ports associated with different ASICs.
When a line card is installed on a 9606R chassis, one-third of its ports are connected to one of the three ASICs. In other words, one-third of the ports on the line card is connected to ASIC 0, the second set is to ASIC 1, and the third set of ports are connected to ASIC 2.
Here’s a visual of the port numbering assignment on the C9400-LC-24C line card with C9600-SUP-1 and C9600-SUP-2 and their ASIC mapping.
You have to use the “enable” command under a Hundred Gigabit Ethernet interface to turn on 100 Gbps support. When the Catalyst 9606R is powered by a C9600-SUP-1, the switch disables the bottom port. For instance, when you enter the commands below on Hu1/0/25, the switch disables the bottom Forty Gigabit Ethernet port, Fo1/0/2.
interface Hu1/0/25 enable exit
When instead of using a SUP-1, you use C9600-SUP-2 supervisor module, the switch allows having all 24 Hundred Gigabit Ethernet ports activated.
You can verify all these ASIC-to-physical port mappings with the command show platform software fed active ifm mapping.
As you can see, for critical port channels, you can spread the port channel member links across ASICs for better performance and redundancy.
StackWise Virtual Dual Active Detection Sample Configuration
If the StackWise Virtual Link is lost, the standby switch will think that the active switch is lost, and therefore, the standby will become active. When you have two active core switches with the same IP addresses on all routed and Switched Virtual (SVI) interfaces, you run into duplicate IP issues.
To avoid this scenario, you can configure a Dual Active Detection link as follows.
interface range TwentyFiveGigE1/5/0/48,TwentyFiveGigE2/5/0/48 stackwise-virtual dual-active-detection exit
Notice that after the StackWise virtual switch is created, your port numbering scheme changes.
The first number represents the chassis ID. The second number tells you the module number within that chassis. And the fourth number is the port on that module.
StackWise Virtual Best Practices
I recommend the following Cisco StackWise Virtual best practices:
- Use a StackWise Virtual domain ID between 1 and 255 to avoid conflict in the network. The default is domain ID 1.
- Use a Switch ID between 1 and 9. I always use 1 and 2. I configure the switch on the left or on top (one switch atop the other) as Switch 1.
- The default Switch priority is 1 and the highest is 15. Cisco recommends increasing the priority of one of the switches to make it more likely to become the active switch. I always configure Switch 1 with a priority of 15 to pre-determine what switch becomes the active switch. To become active, a higher priority is preferred.
- Stack MAC address: Default is infinite. Cisco recommends keeping default settings.
- You should configure the StackWise Virtual link as a multiple-link port channel and spread it across multiple ASICs if possible as well as multi-line cards.
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I hope this post was useful to you.
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