% ERSPAN

+ ERSPAN I
= Build & dissect ERSPAN 1

pkt = GRE()/ERSPAN_I()/Ether()
pkt = GRE(bytes(pkt))
assert ERSPAN in pkt
assert pkt.proto == 0x88be
assert pkt.seqnum_present == 0

+ ERSPAN II
= Build ERSPAN II

pkt = GRE()/ERSPAN_II()/Ether(src="11:11:11:11:11:11", dst="ff:ff:ff:ff:ff:ff")
b = bytes(pkt)
assert b == b'\x10\x00\x88\xbe\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x11\x11\x11\x11\x11\x11\x90\x00'

= Dissect ERSPAN II

pkt = GRE(b)
assert pkt[GRE].proto == 0x88be
assert pkt[GRE].seqnum_present == 1
assert pkt[GRE][ERSPAN].ver == 1
assert pkt[Ether].src == "11:11:11:11:11:11"

+ ERSPAN III
= Build & dissect ERSPAN III with platform specific

pkt = GRE()/ERSPAN_III()/ERSPAN_PlatformSpecific()/Ether()
pkt = GRE(bytes(pkt))
assert pkt[GRE].proto == 0x22eb
assert pkt[ERSPAN_III].o == 1
assert ERSPAN_PlatformSpecific in pkt
assert Ether in pkt

= Build & dissect ERSPAN III without platform specific
pkt = GRE()/ERSPAN_III()/Ether()
pkt = GRE(bytes(pkt))
assert pkt[GRE].proto == 0x22eb
assert pkt[ERSPAN_III].o == 0
assert ERSPAN_PlatformSpecific not in pkt
assert Ether in pkt