This read-only value, from 0 to 15, identifies which specific ring a status-table row describes, since a single switch can be a member of more than one Super Ring simultaneously. An admin uses it to make sure they're reading the status of the correct physical ring when the device straddles multiple loops. For example, ring Id 2 tells the admin the accompanying role and status fields describe the switch's participation in its second configured ring, distinct from ring Id 0's data.