I followed this guide: Layer 2 Configuration Guide, Cisco IOS XE Fuji 16.8.x (Catalyst 9300 Switches) - Configuring Resilient Ethernet Protocol [Support] - Cisco. My topology most closely matches figure 1 "REP open segment" in that guide. However, i have an STP trunk between the two edge switches. The two 'edge' switches in the ring each have a trunk to a router (one each). The switches do no layer 3 routing. The two routers do all routing and are clustered via hsrp to float a vip for each subnet. The clustered pair of routers is the interface between this rep network and the world.
In summary, i have a ring of c9300 switches running REP. Two adjacent switches on the ring uplink to a clustered pair of routers. The routers are not running spanning tree and do not provide passthrough of vlans at layer 2. They are for layer 3 routing of the subnets associated with each vlan in the ring.
I had an issue where, when the rep ring breaks and its topology reconverges, some traffic would stop and not resume. I logged a case with Cisco who advised that it was due to the two edge switches running REP whilst also having a STP trunk between each other. Cisco are coming back to me with a design which uses non-rep edge ports. I'd appreciate wisdom from this community as to what you believe a suitable setup would be.
