Multiple Leaf to Spine Link

[boquiason]

Hi All,

Spine Leaf designs I have seen so far show a single link from Leaf to each Spine and the recommended solution to increase aggregate fabric throughput is to add another Spine. Is it a valid design to have multiple links from Leaf to Spine to achieve the same objective? Any caveats or restrictions?

Thanks.

[Claudia de Luna]

Hi @boquiason

Yes, it is actually usual that you first grow your fabric bandwidth my using multiple fabric links from each leaf to your spines.  If your leaf has 6 fabric uplink interfaces you can take 3 to spine 1 and 3 to spine 2 if you have two spines.  The fabric will use equal cost multipath (Layer 3) to distribution traffic across all the links.  If you have 4 spines you can connect one leaf fabric interface to each spine.

From a cost perspective its most common to run multiple links from the leafs to the spines as long as you have the spine interfaces to support those links (which will of course depend on how many leafs you have in your fabric).  That is really the only caveat (sufficient interfaces on your spines).

The attached design is perfectly valid and very common.

Hope this helps!

Claudia