DX NetOps

Tech Tip:  What is the difference between the attributes IfAlias (0x117Fe) and Internal_If_Alias (0x11f82)?

CA Spectrum Tech Tip by Bill Wolforth, Senior Support Engineer for 8/19/14

Description:

As an example, a scenario where you may wish to use either of these 2 attributes would be in the creation of a policy based on the ifAlias attribute of ports.

Solution:

1. 0x11f82 is an internal value stored in the database.
2. 0x11f7e is an external value read on the actual device. Once it is read this value is copied to the 0x11f82 (internal) attribute. It is not stored in the DB.
3. It would normally be recommended to use the internal 0x11f82 attribute value as requires less work because it does not have to do an external read of the attribute (0x11f7e ) on the device.
4. However this also means that the 0x11f82 internal attribute may not always be the most recent value depending on when it was last read.
5. If you require always the most current attribute value then you should use the external attribute IfAlias (0x117Fe).
6. It should be noted however that if using the external ifAlias (0x117Fe) attribute it will involve more server work, will be slower and could potentially fail if the device was to be unreachable.

Just a little update 

Sometimes depending upon your configuration, you may not be able to use the external ifAlias attribute as it will cause major performance problems with your SpectroSERVER (due to the constant polling/requests for the value). Therefore we changed this functionality in 9.4.

As of CA Spectrum 9.4 instead of using either the external ifAlias (0x11f73) or the internal_If_Alias (0x11f82), a new attribute named X_ifAlias was added.  This attribute is a copy of the devices external ifalias value. This will allow users to create global collections and searches that use the internal attribute (X_ifAlias) which is drastically more efficient.  If you are currently using ifAlias or internal_If_Alias and you upgrade to 9.4, you should update/change your searches to utilize the X_ifAlias attribute.

More information on the X_ifAlias can be found here:

TEC614054

There are a couple of important notes about that attribute in the tech doc.

Cheers

Jay

Thanks Jay.  This is very helpful.

We are currently still using 9.3 and are really making use of the ifAlias attribute, which we are polling regularly. This is because we are using interface descriptions so that we can group those interfaces into global collection. For example, if the interface is marked as a high priority interface alarms will be forwarded to the responsible guys at the customer. There are more uses cases here for using the ifAlias.

I understand that using Internal_If_Alias is not useful as it is not always up-to-date.

And as I understand the information above, X_ifAlias is only updated with a SS restart or by using an update code, so we will keep using ifAlias even if it says that this could cause performance issue.