This attribute indicates the MAC of the device located at the far end
of the VC. This is normally the host device.
This address is inserted in the source address (SA) field of the 802.5
frames sent typically on a token ring interface. This address is
expected in the destination address (DA) field of the 802.5 frames
received, typically from a token ring interface.
When this attribute is defined All Route Explorer (ARE) and Single
Route Explorer (SRE) frames received from the local LAN must
have the DA field matching it, otherwise they are discarded.