MS/TP Max Master Conflict
MS/TP limits the number of nodes that can act as masters (poll for token). Max Master is a trunk-wide parameter; if more masters exist than the configured value, token ring behavior becomes unstable.
Common Causes
- New router, gateway, or controller added with master capability
- Max Master parameter set too low for actual number of masters
- Multiple front-ends or workstations polling the same MS/TP trunk
- Misconfigured Max_Info_Frames or Max_Master causing contention
Fix Steps
- Count all potential masters on the trunk: routers, gateways, workstations, front-ends.
- Set Max Master to at least that count on all nodes (typically 127 max).
- Ensure all devices use the same Max Master value for trunk consistency.
- Reduce masters if possible: route through one gateway instead of multiple.
- Power-cycle the trunk to apply new Max Master settings; allow token ring to reform.