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.