G.8032 Version 2
The concept of sub-rings is introduced to add multiple rings to the main ring. A sub-ring is an incomplete ring that completes its path through the main ring or other sub-rings. The control path for the sub-ring completes either through the implementation of a virtual channel, or by changing the flow of control packets in the sub-rings. Virtual channels are supported through the use of the sub-rings control channel being configured as a data VLAN in the main ring.
You can configure the sub-ring in “no virtual channel” mode, where the control path for the sub-ring is through all the nodes of the sub-ring (including the RPL owner and neighbor). You must be careful, however, to avoid using the sub-ring‘s control channel across the main ring because that will cause a loop. ExtremeXOS supports the use of CFM, in conjunction with Manual Switch (MS), to protect the sub-rings against multiple failures in the main ring.