Posted on August 18, 2020 3:32 am
 |  Asked by Amit Chudasama
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how many spines and leafs can be part of single two-tier Fabric

Answered on August 18, 2020 5:22 am

Hi Amit,

Thank you for contacting Arista.

Number of spines and Leaf devices in Leaf Spine Architecture depends on the design of the network environment and requirement for the type of traffic flow(North-South/East-West).

We can scale the devices based on oversubscription ratio between leaf and spine switches, the bandwidth we need for north-south and east-west traffic flow.

You can refer to the Network Design Requirements section in the below RFC for more detailed info regarding design requirements:




Posted by Alexis Dacquay
Answered on August 18, 2020 10:46 am

Arista support 128-way, it means you can have 128 Spine devices
Of course that mean your Leaf needs 128 uplink, which is possible when there are 256-ports (e.g. 64-ports, breakout as 4x ).
128 ports (32x 4 with breakout) would be used as uplinks
128 ports would be used as access

128 leaves x 128 ports = 16,384 ports

That is with only fixed form-factor switches.

If you do that with modular form factor, instead of "only" 256 ports on the leaves you can have 2000+ , so you can reach over 100k server ports.

If instead of 64x QSFP leaves you use smaller form factors, then you scale would go down. 32-ports QSFP -> half the scale.

All that in only 2-tiers.


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