DOCSIS-CMTS-TOPOLOGY-TYPE is an IPDR Service Definition Schema that defines the RF topology information that shows the connectivities of downstream and upstream channels to the fiber nodes within the CMTS. Revision History: 3.5.1-A.1 Initial version. 3.5.1-A.2 Revised version includes ECN OSSIv3.0-N-10.0914-3 and published as I12. DOCSIS 3.0 Operations Support System Interface Specification CM-SP-OSSIv3.0-I12-100611, Annex O. This IPDR record contains the association of upstream and downstream channels to each unique pair of MD-CM-SG and Fiber Node.