ovs 源mac, 目的src 互换
push:NXM_OF_ETH_SRC[],push:NXM_OF_ETH_DST[],pop:NXM_OF_ETH_SRC[],pop:NXM_OF_ETH_DST[]
1:把src mac推到栈顶
push:NXM_OF_ETH_SRC[]
2:把dst mac推到栈顶
push:NXM_OF_ETH_DST[]
3:从栈顶读取mac存到NXM_OF_ETH_SRC[]
pop:NXM_OF_ETH_SRC[]
4:从栈顶读取mac存到NXM_OF_ETH_DST[]
pop:NXM_OF_ETH_DST[]