There are several best practices that Cisco recommends to follow when
you configure circuits on the ONS 15454. This document uses a lab setup to
demonstrate these best practices.
Note: A circuit that has lost connectivity to the end points is in an
INCOMPLETE state. If you try to delete the circuit, bandwidth can be stranded.
The best practice is to back out, and ensure that the Cisco Transport
Controller (CTC) can see the entire network topology in order to learn the end
points of the circuit, and change the circuit back to an ACTIVE state. Delete a
circuit only when it is restored to the ACTIVE state. If it is not possible to
get the circuit into an ACTIVE state, ensure that you delete all the incomplete
segments of the circuit, and configure the circuit again.
Note: In the lab setup, a Synchronous Transport Signal-1 (STS-1) circuit is
configured from Node A to Node E. The lab setup demonstrates how:
Changes on the nodes can cause the circuit to change from the
ACTIVE to INCOMPLETE state.
You can recover the circuit back to an ACTIVE
A circuit in an INCOMPLETE state that cannot be recovered needs to
have all of its incomplete segments deleted while in the INCOMPLETE
Readers of this document should have knowledge of these topics:
The information in this document is based on these software and
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.
For more information on document conventions, refer to the
Technical Tips Conventions.
This document uses this lab setup:
Figure 1 – Lab Setup
Circuits are normally in the ACTIVE state. In abnormal conditions,
circuits can move into an INCOMPLETE state.
Circuits can move into an INCOMPLETE state when the CTC application
loses its connectivity to the end points of the circuit. The CTC application
can lose connectivity when a part of the network topology is lost (unprotected
fiber break), or when you add parts of the network topology, which the CTC has
not previously learned.
If you try to delete circuits that are in an INCOMPLETE state, you can
strand bandwidth, and cause resources to become unavailable for configuration
on the 15454. The best practice is to back out, and ensure that the Cisco
Transport Controller (CTC) can see the entire network topology in order to
learn the end points of the circuit, and change the circuit back to an ACTIVE
state. Delete a circuit only when it is restored to the ACTIVE state.
If the circuit is damaged and you are unable to get it into an ACTIVE
state, ensure that you know the complete path of the circuit through the
network topology. Then delete all of the incomplete segments of the
If you do not follow the best practices in certain circumstances, you
can corrupt the control blocks. Control blocks instruct the circuits about
which path to take through the Cross Connect (XC) and Cross Connect Virtual
Tributary (XC-VT) cards. The STS and VT circuits that take these paths then
become unavailable for configuration on the 15454. As a result, the bandwidth
and switching capacity through the XC and XC-VT cards are reduced.
In the sample lab setup, a circuit is provisioned from Node A to Node
E. The circuit is fully protected and automatically routed. One of the
strongest features on the 15454 is A to Z provisioning. A to Z provisioning
enables you to specify the source and destination ports, and allows the 15454
nodes to automatically configure the circuit.
Figure 2 – Circuit is Provisioned From Node A to Node
Complete these steps:
Select the Circuits tab from the network level
view to create a single, bidirectional, fully protected circuit with automatic
(A to Z) provisioning.
The Circuit Creation dialog box is displayed:
Figure 3 – Create a Single, Bidirectional, Fully Protected
Circuit with A to Z Provisioning
Specify the circuit name, type, and size in the relevant
Specify the source port of the DS1 card in slot 1 of Node A to
create the STS-1 circuit.
Figure 4 – Specify the Source Port for the STS-1
Specify the destination port for the STS-1 circuit as the DS1 card
in slot 1 of Node E.
Figure 5 – Specify the Destination Port for the STS-1
The circuit confirmation screen prompts you to verify the source
and destination ports:
Figure 6 – The Circuit Information
In the network level view, the right side of the newly created
circuit shows the spans that the A to Z provisioning feature of the 15454
creates automatically. Notice the working and protect spans 3 and 4 for the
Unidirectional Path Switched Ring (UPSR) ring from Node A to Node
Figure 7 – Spans Created by the A to Z Provisioning Feature of
Select Circuit > Maps.
The network topology displays the automatically provisioned path
that the circuits take. The circuit is fully protected against a single fiber
break on any span along its path:
Figure 8 – The Automatically Provisioned Circuits
The linear 1+1 path from Node D to Node E uses the OC-12 card in slot
16 as its working path, and the OC-12 card in slot 17 as its protection path.
The protection path is deliberately removed at Node E:
Figure 9 – The Protection Path is Removed at Node
Complete these steps:
Select Provisioning >
Select the OC-12 protection group.
Click Yes when you are prompted to confirm the
Figure 10 – Delete the Protection Group at Node
When you remove the protection path, Node E sends a Signal Label
Mismatch Failure (SLMF) unequipped path alarm. Node D reports the SLMF alarm on
the active alarms screen:
Figure 11 – The SLMF Alarm
Note: The linear 1+1 protection is not removed until you remove the
protection at both nodes E and D of the linear 1+1 span. If you created a
circuit from Node A to Node D, it still remains fully protected:
Figure 12 – The Protection Path is Removed at Nodes D and
Complete these steps:
Repeat steps 1 through 4 of the Remove the
Protection Path at Node E procedure to remove the protection group at
Figure 13 – Delete the Protection Group at Node
Repeat the steps illustrated in the Configure an
Automatically Provisioned Fully Protected Circuit section to create the
circuit from Node A to Node E. The circuit creation fails because the 15454 is
no longer able to create a fully protected path on the network span from Node D
to Node E:
Figure 14 – Circuit Creation Fails
If a configured circuit loses its end to end connectivity, it goes into
an INCOMPLETE state:
Figure 15 – Circuit Goes into an INCOMPLETE
Complete these steps:
Select Provisioning > Sonet
Select the required SDCC termination, and click
Remove the Synchronous Optical Network (SONET) Data Communications
Channel (SDCC) terminations at Nodes D and E in order to simulate a fiber
Figure 16 – Remove the SDCC Termination
When you remove the SDCC termination at Node E, an SDCC termination
failure is generated. Node D receives and sends the SDCC termination failure to
the active alarms screen. From the network level view, the green line that
links Node D to Node E disappears:
Figure 17 – The SDCC Termination Failure
The circuit you created from Node A to Node E loses its end-to-end
connectivity and goes into an INCOMPLETE state. From the right side of the
circuit display, the span from Node D to Node E is now absent:
Figure 18 – Circuit is in INCOMPLETE
Select Circuit > Maps from the network level
The network topology displays the automatically provisioned
circuits path that is taken. However, now the span from Node D to Node E is
absent, and the circuit terminates at Node D:
Figure 19 – Circuit Terminates at Node D
When CTC connectivity is restored to both end points of the circuit,
the circuit reverts to ACTIVE state.
Figure 20 – Circuits Revert to ACTIVE State
Complete these steps:
Configure the SDCC terminations again on Node D and E.
The green line between Node D and Node E now reappears. Also, the
SDCC termination failure alarms white out:
Figure 21 – SDCC Termination Failure Alarms White
Click the Circuits tab.
Figure 22 indicates that the circuit
from Node A to Node E regains the information on the right side about the span
from Node D to Node E. Also, as the end-to-end connectivity is restored, the
circuit returns to an ACTIVE state:
Figure 22 – End-to-end Connectivity is Restored, and the
Circuit Returns to an ACTIVE State
Select the circuit, and click Map. The path the
circuit takes through the network topology is displayed:
Figure 23 – Circuit Path Through the Network
You can confirm that the same behavior occurs on the other side of
the fiber break. If you had closed and then reopened the CTC session on Node E,
initially CTC knows about this session, and the incomplete circuit that
terminated on it:
Figure 24 – Same Behavior on the Other Side of the Fiber
Configure SDCC terminations on Node E. Node E starts to learn about
the other nodes in the network.
Note: At this stage, the circuit is still in INCOMPLETE
Figure 25 – Configure SDCC Terminations on Node
As the nodes continue to initialize, Node E starts to learn about
the destinations for the incomplete circuit:
Figure 26 – Node E Learns About the Destinations for the
Next, the CTC application learns about all the nodes in the network
and the path to the end points of the circuit. The circuit then reverts to an
Figure 27 – Circuit Reverts to the ACTIVE
If the CTC session closes while the connection to Node E is down, CTC
can only learn about the four nodes on its part of the network segment after a
reconnection. CTC cannot learn about Node E until a valid connection is
established with Node E. Here is the network topology that the CTC learns and
Figure 28 – Network Topology that the CTC
Complete these steps:
In the Circuits tab, select the required
The circuit is in the INCOMPLETE state. The CTC is not able to make
the circuit active because there is no information about the end point of the
circuit on Node E. When you try to delete the circuit, a warning message is
displayed to indicate that if the circuit is active, traffic can be
Figure 29 – Warning Message When You Try to Delete a
Click Yes to confirm the deletion.
A second warning message is displayed to indicate that the deletion
can strand the bandwidth:
Figure 30 – Second Warning Message
Click Yes again.
The circuit is deleted.
Figure 31 – Confirmation of Circuit
However, Node E does not know that the circuit on the other part of
the network segment is deleted. If you start a CTC session to Node E, and
configure the SDCC terminations again, the CTC application is able to explore
outwards from Node E and discover the network setup.
Node E was not in the CTC applications view of the network topology
when you deleted the circuit. Therefore, Node E is unable to restore and
activate the partially deleted circuit. The circuit remains in the INCOMPLETE
state on Node E:
Figure 32 – Circuit Remains in the INCOMPLETE State on Node
The circuit is now damaged. In order to verify this, you must look
at the map view of the circuit.
Figure 33 – Map View of the Damaged
The best practice that Cisco recommends is to delete the damaged
circuit, and create the circuit again.
Ignore the two warning messages that indicate a loss of live
traffic and that bandwidth can be stranded. Click OK on the
deletion completion prompt.
Figure 34 – Deletion Confirmation Prompt
Configure the circuit afresh. See the Configure an Automatically Provisioned Fully Protected
Circuit section for step-by-step instructions.
Figure 35 – Configure the Circuit Again