Language Basics

match(f=v): match packets whose field f has value v

builtin fields are:

Policy	Syntax	Semantics	E.G.
match	match(f=v)	returns set containing packet if packet's field f matches value, empty set otherwise v	match(dstmac=MAC('00:00:00:00:00:01'))
modify	modify(f=v)	returns set containing copy of packet where field f is set to v	modify(srcmac=MAC('00:00:00:00:00:01'))
forward	fwd(a)	returns set containing copy of packet where outport field is set to a	fwd(1)
drop	drop	returns empty set	drop
identity	identity	returns set containing copy of packet	identity
flood	flood()	returns set containing one copy of packet for each port on the spanning tree	flood()
parallel composition	A + B	returns the union of A's output and B's output	fwd(1) + fwd(2)
sequential composition	A >> B	returns B's output where A's output is B's input	modify(dstip=IP(10.0.0.2)) >> fwd(2) match(switch=1) >> flood()

e.g., match(srcip=IP("1.1.1.2")) match(srcmac=MAC("00:00:00:00:00:01"))