[ns] How to refer to different mac in a multi-interface node

[Kok Lim, Yau]

Hi All,

I have 2 interfaces within a node. The interfaces have different  MAC address. 
I'm using 802.11.

In 802.11, index_ refers to an interface mac address. 

My design requires communication between two interfaces at MAC layer. For 
instance, within a node, interface 0 can trigger interface 1 to do something.

My question is, how to refer to different interfaces? The index_ is just a MAC 
address, can't trigger  the interfaces to do something. 

Thank you for your answer. 

Regards,
KL