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 Catalyst 9400 Series Switches are well suited for data closets in today’s ever expanding network system requirements. Today’s businesses rely on stable, fast, and highly available data connectivity. Businesses perform at such a quick pace now and the need to consume data resources is an integral part of most every business function. There can no longer be outages. Slow data connectivity and sluggish system response is directly related to business success. The Cisco Catalyst platform has provided our company with a network foundation that is fast and reliable so that the business can concentrate on what they do best.
The Cisco Catalyst 9400 Series Switches provide reliable connectivity for multiple client device types whether computers, phones, wireless access points, etc.
The Cisco Catalyst 9400 Series Switches has deployment flexibility from traditional IOS-XE deployments to Cisco Catalyst SD-Access and now Meraki monitored solutions.
Multiple switch models allow us to customize each data closet deployment to exactly fit the port density and power-over-Ethernet requirements.
Software needs improvement, where features are added (Stack wise) or removed (GLBP) without solicitation from a wider audience or depreciation, respectively
Software bugs recently in basic features like AAA
Ability to turn off all unused services or features to reduce the attack surface
Cisco CoPP functionality is not like it was on the Cat 6k platform - users cannot create custom policies for use at the control-plane interface
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.
The Catalyst switches definitely have a more robust feature set than the Meraki switches but the Meraki switches are intended for a different use case than the Catalyst switches. We used Catalyst switches in our wiring closets because they fit in better with the topology and feature sets that we wanted to deploy.
Stability - even 10 year old devices are still running and doing the job
Sometimes lines of products are on the market for a very short time (eg. 6800 instant access) - it is hard to buy equipment to make the network bigger.