For operational groups, one or more services follow the controlling service. On node A, there is an ET SAP facing nodes B/C, and on nodes B/C there are SAPs of the Epipe on physical ports facing node A. Each of the PE data SAPs monitor their respective operational groups, meaning they are operationally up or down based on the operational status of the control SAPs. On node A, because the data SAP is on the ET logical port, it goes operationally down whenever the ET port goes down and similarly for going operationally up.
Alternatively, an Epipe service may be provisioned on each node for each G.8031 data SAP (one-for-one service with no fate sharing). On CE node A, there is a G.8031 Ethernet tunnel. The Ethernet tunnel has two paths: one facing node B and one facing node C. This option is the same as the control SAP, but there are no operational groups. However, now there is a BGP-MH site per service. For large sites, operational groups are more efficient.