one of my clients asked arista about bufferbloat issues in their switches.  here was their response.  is their analysis right?

------

Buffer bloat was a relevant on 10/100M switches, not 10Gb switches. At 10Gb we can empty the queue in ~100ms, which is less than the TCP retransmission timers, therefore no bloat. Buffer bloat can happen at slower speeds, but not an issue at the speeds we have on our switches. 

There are some articles regarding bufferbloat on the net, but buffer bloat is not a problem on our switches.  Some of the information regarding bufferbloat sites Internet routers where packets can be held in queues of very large buffers for several seconds, up to 10 seconds which can cause TCP retransmission problems and lower overall application performance when going across the public Internet.

The buffers on the Arista 7500 are 128MB of packet buffers per 10GbE port coupled to a fully arbitrated (VOQ) virtual output queue forwarding system.  At 10Gbps this is ~100msec of buffer capacity which is an order of magnitude from ‘1 second’ and 2 orders of magnitude from the 10 seconds worst case identified in buffer bloat documents.

We (Arista) have switching systems with large buffers and high port count, or low buffers and high port count running one operating system. Buffer bloat is real in systems that would have more than 1.25GB of packet buffer per 10Gb port - none of these systems contribute to the buffer bloat issue.

We position deep buffering switches where lossless performance is necessary.