Hello, I would suggest you another approach: get rid of the link between MDF1 and MDF2 switches and enhance downlink resiliency between IDF and, respectively, each MDF switch by using a Links Aggregation (a LAG between IDF and MDF1 and another LAG between IDF and MDF2).
Get rid of Port Link of type Hybrid.
You have to consider that an interface - physical or logical (as a LAG), doesn't matter - carrying (if necessary) more than one VLAN (more than its PVID) should be set of type Trunk..and in HPE OfficeConnect 1920 Comware 5 jargon/terminology "Trunk" means exactly what it means in Cisco world (a LAG instead is an EtherChannel).
So to summarize and assuming you're starting from a port default state:
- On IDF Switch create two LAGs - say LAG 1 and LAG 2 - with two (or more) physical interfaces each one.
- Set the IDF LAG 1 to carry required VLAN IDs to MDF 1 Switch's LAG 1 (generally there is a PVID = Untagged and one or more VLAN ID as tagged).
- Do the same (to match) on the MDF 1 Switch (MDF 1 Switch will have LAG 1).
- Set the IDF LAG 2 to carry required VLAN IDs to MDF 2 Switch's LAG 1 (generally there is a PVID = Untagged and one or more VLAN ID as tagged)
- Do the same (to match) on the MDF 2 Switch (MDF 2 Switch will have LAG 1).
- Connect IDF cables between LAG 1 (IDF) and LAG 1 (MDF 1), connect cables between LAG 2 (IDF) and LAG 1 (MDF 2)
- Ensure STP is enabled and properly configured on IDF, MDF 1 and MDF 2 switches (use RSTP).
If so (STP is OK) you can eventually interconnect again MDF 1 and MDF 2 with a single link as a sort of backup link in case MDF 1 or MDF 2 will be disconnected by IDF (this inter-switch link will be automatically blocked by STP, this is correct and expected).