Posted on April 1, 2019 5:31 pm
 |  Asked by Imran Ali
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I would like to ask as we are all aware of that Arista DCS-7050T-52 don’t have Stack Port/Module. is there any possibility to Stack the switches. I have four switches and I also don’t want to go with MLAG. please suggest?

Another question:

have two Switches (DCS-7050 x 2(A & B))
One Server two NICs teaming(LACP) (One NIC is connected to Port 17 on Switch A and another NIC is connected to Port 17 on switch B)

I want to Aggregate the Server NICs at Switch Level.So, that server is available all time and also don’t want to waste the resources.Please suggest the all possible solutions.

Posted by Alexis Dacquay
Answered on August 13, 2020 2:48 pm

Hi Imran,

There is no such thing as stacking in the datacenter switches, whether Arista or other. It is not suitable for DC performance.

It might be OK for user access in campus.

But for server connectivity, please look at multi-chassis technology; all vendors propose this for the datacenter, in a form or another. At Arista we provide MLAG multi-chassis LAG (2-ways max) or EVPN Active-active Multi-homing (more than 2-ways).


Why is stacking not suitable for the DC? In short...

  • low performance; both for east-west and south-north. Think about the traffic path from server A to server X on the same stack of 4 you suggest, or fro server A to remote locations (plural)  Y and Z: what will the hashing leads to us as links (inter-stack links; uplinks). Stacking is full of bottlenecks, unequal hop counts.
  • Reliability. I imagine you have maybe at least once suffered from someone plugging the switches in the wrong order, put the wrong priority on one, or wrong config. Maybe the software wasn't updated everywhere to the same level, and after one element failure the stack went in wrong OS and suffered an outage. Stacking isn't meant for Uptime.
  • The convenience of "single management plane" is not what networking is built upon: Isolation of failure domain. One switch, one own's decisions at L2 and L3. No sharing of fate. Ethernet. IP. Arpanet heritage. Designed for sustaining major cases of failures. Stacking is not.


The convenience of single management plane found with stacking is obvious, I agree, but it doesn't win over the resilience of DC technologies like MLAG or EVPN Multi-homing. Keep your management planes and control-planes distinct.

To gain the same operational benefits, simplifying the management plane and gain operational efficiency, please look at automation, Ansible or CloudVision.

If you need to configure 10 things on ports, can there be 1 thing (script? configlets?) that configure those 10 things for you automatically?


I might sound biased, but I would recommend the same, whether you were to implement this on Arista, Cisco or Juniper: no stacking for servers.




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