The ring (segment) number in use on a 802.5 ring. For
bridges supporting RFC 1525, this value is the same as given
by dot1dSrPortLocalSegment for the bridge port attached to
that ring. When tokenRing VLANs are in use, each 'trNet'
VLAN can/does have a different instance of
dot1dSrPortLocalSegment for each physical port. Note that
access to the particuler instance of dot1dSrPortLocalSegment
requires knowledge of how the agent supports the multiple
'contexts' required to implement RFC 1525 for multiple
VLANs; also note that the assignment of ifIndex values may
be different in different 'contexts'.