This MIB module is used to create and monitor cross-connects (horizontal relationships) between peer interfaces on the same network element. Vertical relationships (e.g. between lambdas and the optical fiber in which the lambdas are carried) are represented in the ifStackTable from the IF-MIB. This MIB can be used to model various types of cross-connects between peer interfaces, including time-division (e.g. SDH/SONET, PDH), wavelength (lambda), and spatial switching (e.g. incoming port or fiber to outgoing port or fiber). This MIB does not apply to cross-connects between packet flows (e.g. packets in the same forwarding equivalence class at a MPLS-capable switch or router) or cell flows (e.g. ATM Virtual Path connections or ATM Virtual Channel connections), since there are scalability issues in modeling each packet flow or cell flow as a logical interface. The switching element performing the cross-connect function can be electrical (e.g. SDH/SONET switch) or optical (e.g. passive optical add/drop multiplexer) Cross-connects can be created through provisioning, automatically by the network element, or dynamically by using control protocols (e.g. GMPLS). The cross-connect model includes support for pairs of interfaces used to protect each other (e.g. SONET 1+1 Automatic Protection Switching). Cross-connects to protection interfaces may be shown in this MIB module.