This read-only Counter32 counts CPS-layer Channel Identifier errors, corresponding to errnum 9 in Table 6/I.363.2, meaning a received packet carried an invalid or unexpected CID. It can indicate a configuration mismatch in the CID range set by aal2CpsCIDLowerLimit and aal2CpsCIDUpperLimit versus what the far end is actually using. If this counter increases after the CID limits were changed, the admin should verify both ends of the connection agree on the valid CID range.