- All supported software versions.
VSP 2 and 3 are in a vIST cluster.
VSP 1 has ISIS adjacencies with VSP2 and VSP 3.
VSP 2 and VSP 3 has separate OSPF adjacency with Third party router.
10.1.1.0/24 is learnt by VSP 2 and VSP 3 via ISIS. Both the VSP 2&3 redistribute the same route into OSPF.
When the links are brought up, the VSP 2 and VSP 3 initially has the 10.1.1.0/24 as an ISIS route in the routing table. However after full convergence with OSPF neighbors, the 10.1.1.0/24 is learnt as a OSPF route replacing the ISIS route. Both of the routers shows the other router as the next hop causing a routing loop.