Supported Platforms
Related Documentation
- ACX, M, MX, PTX, QFX, T Series
- Example: Configuring OSPF to Make Routing Devices Appear Overloaded
- Example: Limiting the Number of Prefixes Exported to OSPF
- ACX, EX, M, MX, PTX, QFX, SRX, T Series
- overload
OSPF Overload Function Overview
If the time elapsed after the OSPF instance is enabled is less than the specified timeout, overload mode is set.
You can configure the local routing device so that it appears to be overloaded. An overloaded routing device determines it is unable to handle any more OSPF transit traffic, which results in sending OSPF transit traffic to other routing devices. OSPF traffic to directly attached interfaces continues to reach the routing device. You might configure overload mode for many reasons, including:
- If you want the routing device to participate in OSPF routing, but do not want it to be used for transit traffic. This could include a routing device that is connected to the network for analysis purposes, but is not considered part of the production network, such as network management routing devices.
- If you are performing maintenance on a routing device in a production network. You can move traffic off that routing device so network services are not interrupted during your maintenance window.
You configure or disable overload mode in OSPF with or without a timeout. Without a timeout, overload mode is set until it is explicitly deleted from the configuration. With a timeout, overload mode is set if the time elapsed since the OSPF instance started is less than the specified timeout.
A timer is started for the difference between the timeout and the time elapsed since the instance started. When the timer expires, overload mode is cleared. In overload mode, the router link-state advertisement (LSA) is originated with all the transit router links (except stub) set to a metric of 0xFFFF. The stub router links are advertised with the actual cost of the interfaces corresponding to the stub. This causes the transit traffic to avoid the overloaded routing device and to take paths around the routing device. However, the overloaded routing device’s own links are still accessible.
 | Note: The routing device can also dynamically enter the overload state, regardless of configuring the device to appear overloaded. For example, if the routing device exceeds the configured OSPF prefix limit, the routing device purges the external prefixes and enters into an overload state. You can limit the number of routes exported into OSPF to minimize the load on the routing device and prevent this potential problem. |
Related Documentation
- ACX, M, MX, PTX, QFX, T Series
- Example: Configuring OSPF to Make Routing Devices Appear Overloaded
- Example: Limiting the Number of Prefixes Exported to OSPF
- ACX, EX, M, MX, PTX, QFX, SRX, T Series
- overload
Published: 2012-12-08
Supported Platforms
Related Documentation
- ACX, M, MX, PTX, QFX, T Series
- Example: Configuring OSPF to Make Routing Devices Appear Overloaded
- Example: Limiting the Number of Prefixes Exported to OSPF
- ACX, EX, M, MX, PTX, QFX, SRX, T Series
- overload
