Cisco CAT9K Stackwise vs Nexus 9K VPC

[Nenday]

hello, 
I need a suggestion to change my nexus infrastructure to CAT9K using Stackwise, that I didn't have a lot of knowledge on, 
in fact in Nexus environnement I have this : 

where I use multichassi Port Channel, to ensure real redendency, 
but In my new case I have a little different things, that I have 4 CAT9K 24 ports (in place of just 2 48)
I already made 2 stack (each 2 switch make a stack of 48 ports) and I want make something like peerlink between them ! what is the best way to do that please !
I don't want to make one logical switch 

any suggestion or if someone pass by this way please help

thanks

[MHM Cisco World]

Stack cable connect between stack switch is same as peer link. 

No need to use one data port between SW

MHM

[Nenday]

Cisco CAT9500 didn't Have a stack port or module

[MHM Cisco World]

Cat9500 support stackwise virtual which config between ONLY two SW.

If you config two stackwise virtual (each one have two SW) you CAN NOT connect access SW to both stackwise virtual pairs.

MHM

[M02@rt37]

Hello @Nenday 

The ideal method is to configure a multi‑chassis etherChanel (MEC) between the stacks. 

You simply choose matching ports on each stack (e.g. 10 G/25 G), configure them as a port‑channel using LACP, and ensure the same VLAN/trunk settings.

https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9000/nb-06-cat-9k-stack-wp-cte-en.html

[Enes Simnica]

@Nenday i have a lot of clients with setups like urs. So i will try to be very very short with my answer (good luck to me LOOL). 

alright for redundancy between Catalyst 9300 stacks (similar to Nexus vPC), use StackWise Virtual (SWV). Since u have two stacks (2x2 switches), configure SWV to connect them logically without merging into one switch.

use these configs

1. Set up StackWise Virtual on both stacks using a dedicated port-channel (acts like a peer link) which means that the config will be like this: 

stackwise-virtual  
domain 10  
switch 1 priority 15  
switch 2 priority 14  
interface Port-channel1  
stackwise-virtual link 1 

and repeat this on the second stack with reversed priorities...

2. For multi chassis lag,  u need to connect downstream devcies to both stacks via a portchannel and this works because: SWV provides active/standby redundancy (like Nexus vPC). also this will keep stacks independent and will support cross stack etherchannel for high availability...

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/17-9/configuration_guide/ha/b_179_ha_9500_cg/configuring_cisco_stackwise_virtual.html

https://netseccloud.com/cisco-vss-vs-stackwise-key-differences-explained hope it helps and ping me for more help...

IT WASNT LONG RIGHT hahahha

-Enes

[Joseph W. Doherty]

I already made 2 stack (each 2 switch make a stack of 48 ports) and I want make something like peerlink between them ! what is the best way to do that please !
I don't want to make one logical switch 

Not desiring to make one logical switch is good, as you cannot.

As to best way to interconnect the two StackWise Virtual pairs, that would be via Etherchannel between those two pairs.

Minimally something like:

You can, of course, use more than two links (just remember you'll like want to keep an equal number of member links between each member).  Also pay attention to your choice of Etherchannel hashing choice.

[Joseph W. Doherty]

BTW, also I want to mention, StackWise Virtual avoids using peer links.  So, ideally, all connections to a StackWise Virtual switches should be to both peers, which often is NOT the case for many hosts.

For example, in your original Nexus vPC diagram, all hosts connected to SW1, might nicely use both Etherchannel links to the Nexus switches.

With StackWise Virtual, in the diagram I provided all hosts with connections to, say, the left side switch, would normally only use its Etherchannel link.  To obtain benefit of the other Etherchannel link, you would need to disconnect a host from a left side switch and connect it to a right side switch.

For edge switches, with singlely connected hosts, traditional StackWise is usually a better choice.

[Joseph W. Doherty]

Oh, one other point.

Since the 9Ks are L3 switches, you could route between the two StackWise Virtual pairs (across my diagram's green links), using Etherchannel or not.

[Nenday]

Thank you Joseph for your support

I'll try this and back with feedback