O-UNI offers the ability to establish OIF standards-based connections
through a SONET/SDH-based heterogeneous optical network. These connections can
be made across optical transport networks (OTNs) composed of Cisco equipment or
third-party vendor equipment.
An OTN provides transport services to interconnect the optical
interfaces of O-UNI client devices, such as IP routers and SONET ADMs. Two routers running
Cisco IOS XR software
with O-UNI client (O-UNI-C) support are connected to SONET/SDH cross-connects,
which provide O-UNI Network (O-UNI-N) services. These cross-connects sit at the
edge of the OTN, and O-UNI client devices may request services from them. The
client devices have no knowledge of the OTN structure, and all services are
invoked at the edge of the OTN. These services include connection
establishment, deletion, and query for a given data link, where a data link
corresponds to a unique SONET/SDH interface on an O-UNI-C device.
To complete a connection request, an O-UNI-N node needs a database to
determine its route within the OTN. The algorithms used to determine the
connection path, although not standardized in the OIF’s O-UNI 1.0 standard,
must consider the connection characteristics requested by the O-UNI-C device,
including connection bandwidth, framing type, cyclic redundancy check (CRC)
type, and scrambling.
Routers request O-UNI services using the following RSVP messages:
These RSVP messages are transported over IP Control Channels (IPCC)
between the router and the O-UNI-N device. The IPCCs rely on IP connectivity
between O-UNI-C and O-UNI-N devices, represented in dotted lines.
When services from the OTN are requested, the following parameters are included
in the RSVP messages transmitted:
Unique data link identifier
Framing type requested (that is, SONET or SDH)
CRC 16 or 32
IP address of the node to receive the request
A unique identifier exists for every interface participating in an O-UNI
connection. This identifier consists of a TNA and an interface ID. The TNA
addresses are unique within the OTN, and represent the address of one or more
data links between an O-UNI-N device and an O-UNI-C device.
Cisco IOS XR Software
supports the use of IPv4 TNA addresses.
The interface ID is used to uniquely identify a given data link
interface connected between an O-UNI-N device and an O-UNI-C device. The
interface ID is a 32-bit value with local significance, generated by the device
on which an interface resides; for example, a POS interface on a router
connected to an O-UNI-N device would have an interface ID generated by the
router and is only unique on this router. To avoid reconfiguration of LMP
information, it is important that the interface ID values are persistent across
control plane restarts and router reloads.
To establish an O-UNI connection, the messaging exchanges must include
data link information from other devices. This information is provisioned using
a static version of the LMP. The LMP commands allow the provisioning of the
TNA associated with the data link. This value is assigned by the
operator of the OTN.
Interface ID of the neighboring device is the interface ID on the SONET/SDH cross-connect that is referred to as the
remote interface ID.
Node ID of the data link adjacent device is the IPv4 address that sends the RSVP messages to a directly attached
Local information is configured to enable the establishment of O-UNI
connections. This information includes:
Router ID used as the source IPv4 address for RSVP messaging.
This value is also configured on neighbor devices. Note that the terms node ID
and router ID are often used synonymously. Node ID represents the generic term,
while router ID refers to the node ID of a router.
TNA of the data link on which to terminate the connection.
The operational mode of the interface that participates in an O-UNI
connection. This interface can be configured to only terminate a connection or
to initiate a connection.