Showing results for 
Search instead for 
Did you mean: 

A Cisco 7500 series router displays the %RSP-3-RESTART: cbus complex error message


Core Issue

A cbus complex occurs when the router needs to recarve its packet memory (known as MEMD). All the interface processors are reloaded. Each IP downloads its microcode from the Route Switch Processor (RSP), which causes a traffic interruption of approximately two minutes.

One after another, the interface microcodes are downloaded, so the length of the interruption depends on the number of interfaces in the router. The packet memory recarve causes a short traffic interruption of a few seconds.

This message is displayed when a cbus complex occurs:


%RSP-3-RESTART: cbus complex

These are the causes for this error:

  • The microcode reload command is issued.
  • The Maximum Transmission Unit (MTU) size changes in the configuration.
  • An interface, such as an interface (xIP), crashes.
  • An output frozen condition is detected on an interface.
  • Some form of the error condition (such as the parity error) is present on the CyBus, or in the MEMD. The CyBus is the bus linking the RSP and the IPs.


If the microcode reload command is issued, or an MTU size configuration change is done, then the cbus complex is normal. In this case, there is no cause for concern.

If other error messages accompany the %RSP-3-RESTART: Cbus Complex error message, such as %VIP2 R5K-1-MSG messages, parity error messages, or output stuck messages, refer to one of these  documents:

For more information on the %RSP-3-RESTART: cbus complex message, refer to the Troubleshooting section of What Causes a "%RSP-3-RESTART: cbus complex"?.

When Problem Occurs

After software configuration change


Error Messages and Warnings


CreatePlease to create content
Content for Community-Ad
July's Community Spotlight Awards