If you need to obtain a MIB for a particular vendor's device, the best approach is to use one of the several MIB repository sites available on the Internet.
You may also try to obtain a vendor's MIB directly from their official site, as it may be more up to date in comparison to the ones listed on MIB repository sites.
Here is a list of common MIB repository sites you may use to search for a vendor-specific MIB: mibDepot, OiDViEW.
