When modeling devices that support Cisco's CatStackApp functionality, the Internal_If_Alias (0x11f82) attribute does not match the devices actual ifAlias (0x11f7e) entry for ports. This is because the Internal_If_Alias attribute was designed to be only used internally by Spectrum. The attribute is used as part of an inference handler to keep track of the interface table information. Depending upon the device information, Spectrum may set the Internal_If_Alias to a value that does not match the external ifAlias on the device. This is functioning as designed.
There may be a need to utilize the value of an interfaces ifalias as querying or using the external ifalias attribute (attribute 0x11f7e) in Spectrum, this is very expensive and should not be used. In Spectrum 9.4, a new attribute named X_ifAlias is added, which is designed to be a copy of the devices external ifalias value. This will allow users to create global collections and searches that uses the internal value instead of the external value.
This is resolved in 9.4 for Spectrum by Defect number 303356.
There are a few considerations for this change:
- The X_ifAlias(0x13224) attribute will attempt to update on SS startup. If the device is DOWN when the SS starts up, the X_ifAlias(0x13224) may not be in synch with the external ifalias since external ifalias is a read from the device.
- The X_ifAlias(0x13224) does NOT update when running a model reconfiguration. It only updates at SS startup and by using the update action code of 0x10411 (from CLI) -- this can be scripted or customized into event procedures if need be.
The release note entry will be similar to this:
Symptom:Internal_If_Alias is sometimes overwritten with internal Spectrum data.
Resolution:Internal_If_Alias is a reserved internal attribute that is not always intended to mirror the value of the external
ifAlias attribute. A new attribute, X_ifAlias, was created to serve this purpose.
This will also be resolved in hotfix patch H02 for 9.3 when released.