Cisco NCS 1010 Optical Applications Configuration Guide, IOS XR Release 26.x.x

Topology discovery and communication using OSPF in NCS 1010 nodes

Updated: September 19, 2026

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This topic explains how NCS 1010 nodes use OSPF and its enhancements to discover and communicate optical link topology, including node types and spectral bands.

NCS 1010 nodes and their optical applications rely on OSPF (Open Shortest Path First) protocol to automatically discover and share network topology information. An enhanced version of OSPF is implemented to support the unique requirements of optical networks deployed on NCS 1010. This reference summarizes the key attributes and mechanisms of OSPF-based topology discovery and communication in this context.

Topology discovery

Optical applications on the NCS 1010 must identify both OLT-OLT link topology and adjacent nodes at the span-level. Link-level applications require a comprehensive view of the OLT-OLT link topology.

OSPF usage

NCS 1010 devices use OSPF to detect changes in topology, flood link-state updates to neighboring routers, and rapidly converge on an accurate network map. Each OSPF-enabled device updates its internal topology view in response to changes.

Enhanced OSPF

The version of OSPF used on NCS 1010 supports a new link-state advertisement attribute. This attribute advertises node type and optical spectral band, ensuring that applications can recognize node roles and the bands on which they operate.

These OSPF enhancements enable NCS 1010 nodes and their applications to maintain an up-to-date, detailed understanding of both optical connectivity and spectral allocation in the deployed network.

IPv6 and OSPFv3 support

From R26.3.1, IPv6 support is supported on Gigabit Ethernet interfaces using OSPFv3.

IPv6 support limitation

DCN extension for NCS 1010 is not supported with this feature.

Configure OSPF on an NCS 1010 node

Use this task to include NCS 1010 in OSPF-enabled networks.

You must configure the router ID during OSPF configuration on NCS 1010 nodes.

See Implementing OSPF for description of the concepts and tasks necessary to implement OSPF on Cisco IOS XR.

Procedure

Use these commands to configure OSPF on an NCS 1010 OLT node.

Example:


configure
router ospf process-name
router-id router-id
distribute link-state
nsf
network point-to-point
redistribute connected
area area-id
interface Loopback1
interface GigabitEthernet0/0/0/0

Use these commands to configure OSPF on an NCS 1010 ILA node.

Example:


configure
router ospf process-name
router-id router-id
distribute link-state
nsf
network point-to-point
redistribute connected
area area-id
interface Loopback1
interface GigabitEthernet0/0/0/0
interface GigabitEthernet0/0/0/2

NCS 1010 nodes will participate in OSPF routing, which enables inter-node topology discovery and communication.

Configure OSPFv3 for IPv6 topology discovery

Configure OSPFv3 when optical applications must use IPv6 adjacency over Gigabit Ethernet interfaces for topology discovery.

IPv6 support on Gigabit Ethernet interfaces enables optical applications that depend on OSPF adjacency, such as Automatic Power Control (APC), Automatic Line Control (ALC), span loss, Raman tuning, Optical Time Domain Reflectometer (OTDR), and Raman safety.

Note

OSPFv3 router IDs use IPv4 format. In dual-stack migration scenarios, keep the OSPFv2 and OSPFv3 router IDs the same to preserve common topology identifiers.

Before you begin

Identify the loopback interface and Gigabit Ethernet interfaces that participate in IPv6 topology discovery.

Procedure

Configure an IPv6 address on the loopback interface.

Example:


RP/0/RP0/CPU0:ios# configure
RP/0/RP0/CPU0:ios(config)# interface Loopback1
RP/0/RP0/CPU0:ios(config-if)# ipv6 address 2001:DB8:1::1/128

Enable IPv6 on the Gigabit Ethernet interfaces that form OSPFv3 adjacencies.

Example:

RP/0/RP0/CPU0:ios(config)# interface GigabitEthernet0/0/0/0
RP/0/RP0/CPU0:ios(config-if)# ipv6 enable
RP/0/RP0/CPU0:ios(config-if)# exit
RP/0/RP0/CPU0:ios(config)# interface GigabitEthernet0/0/0/2
RP/0/RP0/CPU0:ios(config-if)# ipv6 enable

The ipv6 enable command creates a link-local IPv6 address. Configure a global IPv6 address on the interface only if your deployment requires one.

Enter OSPFv3 router configuration mode.
Example:
```
RP/0/RP0/CPU0:ios(config)# router ospfv3 1
```

Configure point-to-point operation, the router ID, and link-state distribution.

Example:

RP/0/RP0/CPU0:ios(config-ospfv3)# network point-to-point
RP/0/RP0/CPU0:ios(config-ospfv3)# router-id 192.0.2.1
RP/0/RP0/CPU0:ios(config-ospfv3)# distribute link-state

Add the loopback and Gigabit Ethernet interfaces to area 0.

Example:

RP/0/RP0/CPU0:ios(config-ospfv3)# area 0
RP/0/RP0/CPU0:ios(config-ospfv3-ar)# interface Loopback1
RP/0/RP0/CPU0:ios(config-ospfv3-ar-if)# exit
RP/0/RP0/CPU0:ios(config-ospfv3-ar)# interface GigabitEthernet0/0/0/0
RP/0/RP0/CPU0:ios(config-ospfv3-ar-if)# exit
RP/0/RP0/CPU0:ios(config-ospfv3-ar)# interface GigabitEthernet0/0/0/2

Commit the configuration.
Example:
```
RP/0/RP0/CPU0:ios(config)# commit
```

The router can establish OSPFv3 adjacency over IPv6-enabled Gigabit Ethernet interfaces for topology discovery.

What to do next

Verify the OSPFv3 neighbor state and optical topology before you validate dependent optical applications.

Verify and troubleshoot OSPFv3 topology discovery

Verify OSPFv3 topology discovery after you configure IPv6 support on Gigabit Ethernet interfaces.

Topology discovery must complete before OSPF-dependent optical applications can use the IPv6 topology. Use these checks when an adjacency does not come up or the optical topology is not discovered.

Before you begin

Configure OSPFv3 and enable IPv6 on the Gigabit Ethernet interfaces that connect adjacent nodes.

Procedure

Verify the OSPFv3 neighbor state and confirm that the output shows the adjacent router ID, connected interface, and a neighbor state of FULL .

Example:

RP/0/RP0/CPU0:ios# show ospfv3 neighbor
Neighbors for OSPFv3 1

Neighbor ID     Pri   State       Dead Time   Interface ID   Interface
192.0.2.2       1     FULL/ -     00:01:39    18             GigabitEthernet0/0/0/0

Total neighbor count: 1

Verify the end-to-end optical topology.
Example:
```
RP/0/RP0/CPU0:ios# show olc topology
```
If the topology is not discovered, check active system alarms.
Example:
```
RP/0/RP0/CPU0:ios# show alarms brief system active
```
Look for the Neighbour not found alarm on the affected OTS controller.
If the Neighbour not found alarm is active, verify the optical controllers and data path.
- Verify that the OTS and OSC controllers are not in enabled state.
- Verify that data path alarms, such as loss of signal or loss of continuity, are not present on the OTS or OSC controllers.
- Verify that the OSC controllers receive the expected power and optical signal-to-noise ratio on both ends.
Verify that the Gigabit Ethernet interfaces are in no shutdown state.
Example:
```
RP/0/RP0/CPU0:ios# show interfaces GigabitEthernet0/0/0/0 brief
```

OSPFv3 neighbor state and optical topology discovery are verified, or the failing optical or Gigabit Ethernet condition is isolated for further correction.

Configure OSPF cost

Use this task to identify the best route when there are two equal-cost routes to the same destination.

Table 1. Feature History
Feature Name	Release Information	Description
Configure OSPF cost	Cisco IOS XR Release 7.11.1	To identify the best route, OSPF path computation uses the link cost. The system calculates the cost based on the available interface bandwidth. From this release onwards, you can set a user-defined cost value using the costvariable in the router ospf command. As a result, this feature enables you to set a specific route when there are two equal-cost routes to the same destination.

Cost is the metric used by OSPF. You can use the cost command to explicitly specify the network interface for OSPF path calculation.

Note

The cost of the link is inversely proportional to the bandwidth of the link.

Procedure

Use these commands to configure OSPF cost.

Example:


configure
router ospf process-name
router-id router-id
area area-id
interface Loopback1
interface GigabitEthernet0/0/0/0
cost cost

See cost (OSPF) for different command modes and usage guidelines to implement cost OSPF on Cisco IOS XR software.

The interface cost used by OSPF for path calculation is explicitly specified.

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