Portability of N-Series DFE Modules and Configurations

FAQ_User — Sat, 23 Nov 2013 04:35:00 GMT

Article ID: 5037

Products
Matrix N-Series
DFE

Changes
Swapped out a chassis
Swapped out a slot module

Symptoms
Lost system configuration
Lost system firmware

Cause
The DFE N-series modules save their system switching configuation to NVRAM automatically, and save their system routing configuration to NVRAM upon execution of a 'write file' command (5386). This NVRAM-based system configuration is tied to the MAC Address of the chassis in which they are inserted.

Upon installing any DFE module into a chassis other than what it saw at last power-up, initially the configurations will revert to defaults in NVRAM of that module.

If a module is installed into a chassis having a functioning DFE system, then the running system firmware will be downloaded into Flash and implemented (see 5131 for a related point). Then, the running system configuration will be downloaded into NVRAM. If the newly installed module is of the same type as its predecessor in that slot and its port count is the same (a 7G-6MGBIC(-A/-B) Network Interface Module was not added or removed (9901)), the replacement module will take on the configuration assignments relevant to its predecessor. Otherwise, the configurations for that slot will revert to defaults in NVRAM of all modules in the entire system.

When a DFE is powered up in a 6C105 chassis (5275 for allowed models), each module acts as its own standalone DFE system, so the above sequence of events only happens in a 6C107 or 7C107 chassis.

The overall design allows for efficient configuration and upgrading of modules, especially in cases of equivalent replacement in a running system. However, care should be exercised when considering swapping a DFE system to a new chassis or swapping dissimilar modules between slots, for troubleshooting or any other purpose, to avoid loss of a system configuration.

Solution
FAD (Functions as Designed)

It is wise to save your NVRAM-based distributed configuration to a slot-specific file, by means of the 'show config outfile' command, to make your configuration portable and guard against its loss. If at any time the NVRAM-based configuration is no longer available, then use of the 'configure' command will boot the system off of the saved configuration file, re-distributing it. These commands are discussed in 5035.

It is also a good idea to save a copy to more than one module in the system, as insurance in the event of configuration loss in addition to failure of the one module containing the saved configuration file.

Hint: When slot configuration loss is being recovered, and either retyping the slot configs or rebooting the entire system onto the previously saved configuration file are less than practical options, another possibility is to edit a copy of the saved configuration file so that it contains only the missing slot configurations. If you then "configure...append" using that file, it should neatly replace the missing slot configs "on the fly". If you pre-stage the source file prior to the module swapout, the entire operation should be relatively seamless to the continued operation of the system.

See 5335, for more about configuration file portability.
See 5036, about removal/replacement of DFE modules.

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Portability of N-Series DFE Modules and Configurations