I love learning about network hardware, but I’ve always found it difficult to get detailed information on ASICS. We had a great presentation from Dave Zacks on the Cisco 3850 programmable ASIC at the Cisco Live Europe Tech Field Day event.
I received the question below from reader Ned as a comment on my 24-port ASIC post and thought that the discussion was worth a post of it’s own. …Would you be able to speak a bit about the actual physical path or packet flow a packet takes inside the switch itself and how does the hardware forwarding take place within the switch and asic. When does packet get sent to the Asic. Is it happen on ingress or on egress? When…
Modern top-of-rack switches (or TORs) run at line rate and are non-oversubscribed. This means you get non-blocking [1] port-to-port throughput within the switch ASIC at the line rate of the front panel ports. Almost all TOR switches use a single switch ASIC and the industry demanded port-density on a single ASIC, and the manufacturers delivered. The list below shows the 10Gbps port density evolution of the Broadcom StrataXGS product line. The Intel Fulcrum ASIC evolution isn’t shown here but looks very similar….