can we connect two leaf together

[kirankelkar10]

hi, 

can we connect two leaf together.

[balaji.bandi]

what is the use case here to connect leaf to leaf? when there is a spine available?

[kirankelkar10]

hi, @balaji.bandi 

I heard from my manager yesterday that we can connect leaf to leaf in some cases , so i was just wondering if anyone can light some shed on it 

[Claudia de Luna]

I am not aware of any case where connecting two leafs together is a valid ACI topology.  In fact ACI has a protocol, MCP (aptly named Mis Cabling Protocol) , to specifically avoid issues caused by connecting two leafs or two spines together.

From one of my favorite ACI resources:
https://unofficialaciguide.com/2018/03/27/using-mcp-miscabling-protocol-for-aci/

Remember that the fabric does not participate in Spanning Tree so adding additional paths is not supported and could cause issues (hence MCP).

[balaji.bandi]

yes, you can extend the network to connect leaf.

check below is that your case?

https://www.cisco.com/c/en/us/td/docs/dcn/whitepapers/cisco-application-centric-infrastructure-design-guide.html

[kirankelkar10 · Accepted solution]

hi, 

I guess we can use by cisco aci multi tier architecture https://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centric-infrastructure/white-paper-c11-742214.html

[RedNectar]

Hi @kirankelkar10 ,

I hope you are aware of the limitations of ACI Multi-Tier architecture - from your reference document:

• Only Cisco Cloudscale switches are supported for Multi-tier spine and leaf.

  • Spine: EX/FX/C/GX/GX2 spines (For example, Cisco Nexus 9332C, 9364C, 9316D-GX, and 9500 with EX/FX/GX linecards)

  • Tier-1 leaf: EX/FX/FX2/FX3/GX/GX2 except Cisco Nexus 93180LC-EX

  • Tier-2 leaf: EX/FX/FX2/FX3/GX/GX2

[RyanMartin77123]

There are also some exceptions to this rule that can be applied with using ACI Physical Remote Leaf. I believe this is limited to direct vPC peer links though to facilitate orphan port switching without needing to involve upstream IPN router.