Barefoot "Tofino": 6.4 Tbps whitebox switch silicon?

Thu Jun 16 11:54:54 UTC 2016

> I do think p4 is very interesting, but is it really much different from
> openflow? Which...umm ... Did not succeed in the market.

P4 is quite different from OpenFlow.  The various generations of the OpenFlow specification assume a fixed-format packet header with an ever increasing number of header fields (from 12 in OF 1.0 to 41 in OF 1.4), a fixed set of packet-processing actions, and so on. P4 allows programmable parsing and flexible match-action processing.  In P4, the program tells the data plane how to act; in OpenFlow, the way the data plane can act is “baked” in advance.  So, OpenFlow 1.x can be one of many *programs* you can write in P4, whereas many other P4 programs can exist.  For some discussion of the differences, see

  Clarifying the differences between P4 and OpenFlow
  http://p4.org/p4/clarifying-the-differences-between-p4-and-openflow/ <http://p4.org/p4/clarifying-the-differences-between-p4-and-openflow/>

— Jen