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.
CenturyLink Ethernet Services (now known as Lumen) in our area is one of only a few options for fiber service. They have a really large infrastructure and offer competitive pricing with comparable speed to others. We found there was much to be desired in the customer service department. When we had techs onsite to assist in setting up it was fine but there was an issue with the additional networking equipment which caused the service connection to be delayed... Then once that problem was fixed we attempted to get help in the final configuration for many weeks.
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.
AT&T I would say is the leader within this area in terms of handling any large-scale deployments and their services are awesome. No connectivity issues at all and no latency in feedback. Server deployments are handled very effectively, that's not the case with century link. Of course, security is second to none with AT&T.
