Core and data center applications are the strengths of Arista products. The distribution layer is also a good fit. For the access layer, it would be more of a niche product.
Cisco is a name well known in the IT field. The technology is tried and true and they have built a reputation on a solid platform. Though many people do not like the cost of the devices and the continued fees associated with long term ownership, you get what you pay for. I dont hesitate to recommend Cisco because I know people will get a solid product that will last a long time.
Easy setup and configuration. While the web UI has its quirks, setting up VLANs and other tasks which can be exceedingly complicated on other switches, are much easier on Cisco SG switches. You also have the ability to upload an existing configuration to switches, which can speed up the task of deploying many identical switches.
Features for the price. Getting a 48 port L3 switch with PoE+ for less than $2,000 is a great value.
Reliability. We have hundreds of the SG switches in dozens of client sites, many in harsh conditions, and they just keep going.
The web UI has taken a turn for the worse with the latest firmware on the SGx50 models -- the bifurcation between basic and advanced modes and the changes to the way VLANs are modified is a step backward in my opinion.
The power bricks on smaller models are enormous. I'm sure, however, keeping this circuitry external to the switch is what keeps my switches running year after year in hot environments.
Fans can be a bit loud on larger switches -- this is true of pretty much any 1U device though.
I have used the Catalyst 6500 series in the past. From my point of view, the Arista surpasses the Catalyst on just about every front. Originally we were planning on implementing the Nexus 7000/7700 series switches for our core. Though a little more feature rich, it did not provide features we needed that the Arista did. The Nexus also was a confusing and complex platform to work with. Also, the Nexus was a significantly more expensive solution. Although very happy with the Arista switches we may evaluate the Aruba HPE 8400 chassis-based switches along with Arista switches in the future.
Cisco is more enterprise level, more reliable, and generally more feature rich but also very expensive. That being said old or refurbished Cisco switches are much more affordable and in comparison to even new switches from the competitor they are still a great value even though they are used. I like Ubiquiti switches as well but Cisco is usually better overall.
