The (conceptual) table listing the interfaces that are members of a particular group. There are two MIB tables that are suitable for reading (G,I) state - mgmdRouterCacheTable and mgmdRouterPerEntCacheTable. These tables contain the same objects, but their indexing is different. For IGMP snooping, the administrator must read the mgmdRouterPerEntCacheTable. The mgmdRouterCacheTable is not supported (because a single row in that table would correspond to multiple objects, one per bridge domain). When not performing IGMP snooping, the administrator can use either table. In systems in which there are a large number of Router entities, there might be a performance benefit to using the mgmdRouterPerEntCacheTable for queries for which only a subset of Router entities are of interest. For example, if an entity index corresponds to a particular line card, and the administrator is interested in (G,I) state for only one line card, then walking this table for a particular entity index returns the (G,I) state for the interfaces on that line card only (whereas mgmdRouterCacheTable returns (G,I) state for all interfaces on the device). (The possible performance benefit arises because to get the rows in mgmdRouterPerEntCacheTable, MIB Manager queries a single Router entity per row, whereas to get the rows in mgmdRouterCacheTable, MIB Manager queries every Router entity per row).