Specifications

8-5
Cisco MGX 8850 (PXM45) and MGX 8950 Software Configuration Guide
Release 3, Part Number 78-14788-01 Rev. C0, January 2004
Chapter 8 Switch Maintenance Procedures
Replacing Cards with the Same Card Type
Replacing PXM45 and PXM45/B Cards
PXM45 front and back cards can be replaced when the switch is operating. If a PXM45 is operating in
standalone mode, all calls are interrupted until the PXM45 is replaced and operating correctly. If the
switch is using redundant PXM45s, enter the switchcc command, if necessary, to ensure that the card
you want to replace is operating in standby mode.
Because the PXM45 front and hard disk cards store configuration information that controls switch
operation, a nativity check is performed each time a PXM45 front card or hard disk card is added or
replaced. If a PXM45 is configured in a Cisco MGX 8850 or Cisco MGX 8950 switch, the backplane
serial number is stored on the PXM45 front card and on the PXM45 hard disk card. If a PXM45 card is
inserted into a chassis or the card is reset with a command such as resetsys, the nativity check is run to
determine if the PXM45 cards are native to the chassis. If the chassis serial numbers configured on all
PXM45 cards match the switch chassis serial number, the cards are all native and no special action is
required.
The purpose of the nativity check is to resolve configuration differences between PXM45 cards. Some
configuration is stored on the PXM45 front card, and some information is stored on the PXM45 hard
disk card. This information includes the runtime software version to be used. The actual runtime
software is stored on the PXM45 hard disk.
Note When you replace a PXM45 or PXM45/B card, the replacement card uses the boot software stored on
the replacement card and the runtime software configured for slots 7 and 8. If the boot software stored
on the replacement card is not the correct version, you should upgrade it while the card is operating in
standby mode. For instructions on upgrading boot software, see Appendix A, “Downloading and
Installing Software Upgrades.”
If one or more cards are replaced, the nativity check identifies which cards are new to the switch chassis
and uses the nativity check results to determine which cards hold the valid configuration. This feature
can automatically respond to most configuration mismatches, but some mismatches do require a manual
response.
When a switch cannot automatically resolve a nativity check conflict, establish a console port session
through the corresponding PXM-UI-S3 card and enter the shmRecoverIgRbldDisk command. This
command ignores the nativity check and configures the entire switch according to the configuration on the
hard disk.
The following sections describe how the automatic response feature works for standalone and redundant
PXM45 installations, and how to respond when the system cannot automatically resolve conflicts.
Automatic Response for Standalone PXM45 Installations
For standalone installations, the nativity check feature detects and responds to PXM45 cards as shown
in Table 8-1.