This document describes one reason for the failure of the STM-4 to come
up during transport through the network of a service provider. This document
also provides a solution to the problem.
Cisco recommends that you have knowledge of Cisco ONS 15454.
The information in this document is based on Cisco ONS 15454.
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
Technical Tips Conventions for more information on document
In the term VC-4-4C, the first 4 represents the VC-4 formatting type
and the second 4 stands for the total width of the flow, in VCs (see
Figure 1 – VC-4-4C
Contiguous concatenation has been a part of the TDM specification for
quite some time. The TDM payload containers are transported and switched across
the SDH network as a single module. The first SDH container payload pointer is
set to normal mode, and the subsequent payload pointers are set to
concatenation mode, and thus link all the units together.
Two ONS15454E nodes with TCC2P and STM16 backbone run ONS 15454 version
6.0. When you try to to create a point-to-pint STM-16 that transports data over
the SDH network of a service provider, the STM-16 network fails to synchronize
through the third party network (see Figure
Figure 2 – Topology
The output of the OC/STM card is whetever the XC sends. So if you
create a circuit between two OC/STM cards, the output is just what the cards
receive. The OC/STM cards forward what they receive, and do not affect the
overhead and payload.
The service provider needs to channelize the STM-16 exactly as the
circuits are created in the ONS nodes. If the service provider does not
channelize the STM-16 properly, only the first circuit operates (see
Figure 3 – Incorrect Transport
In this particular case, you do not have a "clear channel" span that
connects the ONS15454s. Therefore, the ONS15454s must have the service provider
provision these STM-16s to match your provisioning. So for example, if you
create a 4c (AU-4-1 through AU-4-4), the service provider also has to create
this on the STM-16 (see Figure 4).
Figure 4 – Correct Transport