OAM is a set of tools that have been used to provide network fault indication, performance information, fault localization, data and diagnosis functions.
In different standard bodies usage of OAM is slightly different thus it creates a confusion among the engineers.
Operations And Maintenance (OAM): A group of network management functions that provide network fault indication, performance information, and data and diagnosis functions. ATM OAM ITU-T I.610 [ITU-T-I.610] is an example specification that uses this expansion of the “OAM” acronym.
Operations, Administration, and Maintenance (OAM): A group of network management functions that provide network fault indication, fault localization, performance information, and data and diagnosis functions. Examples where this acronym is used are Clause 57 of IEEE 802.3-2008 [IEEE.802.3-2008] and ITU-T Y.1731 [ITU-T-Y.1731].
Similar definitions from the ITU-T and the IEEE. But they don’t explain much what O , A and M stands for.
In the RFC 6291 OAM and its functions are very clearly explained.
The ” O ” in OAM :
Operation activities are undertaken to keep the network (and the services that the network provides) up and running. It includes monitoring the network and finding problems.Ideally these problems should be found before users are affected.
The ” A ” in OAM :
Administration activities involve keeping track of resources in the network and how they are used. It includes all the bookkeeping that is necessary to track networking resources and the network under control.
The ” M ” in OAM :
Maintenance activities are focused on facilitating repairs and upgrades — for example, when equipment must be replaced, when a router needs a patch for an operating system image, or when a new switch is added to a network. Maintenance also involves corrective and preventive measures to make the managed network run more effectively, e.g., adjusting device configuration and parameters.
Some Organizations use the term ” Provisioning ” as part of an OAM. But according to the IETF they are different terms and Provisioning can be defined as ” activities involve configuring resources in the network to support the offered services. This might include setting up the network so that a new customer can receive an Internet access service. “
In general, Provisioning is used to configure the network to provide new services, whereas OAM is used to keep the network in a state that it can support already existing services.
The M in OAM is used for the maintenance activities according to the IETF as I stated above, not for the Management. Management is another networking function which is used as interchangeable by some organizations. IETF also uses Management separately. If you want to use abbreviation for all , their suggestion is to use OAM & Mgmt or shortly O&M.
Although Management function is not explain in the RFC , In general management functions run between user or Network management system and the Network Element so it tends to be a vertical whereas OAM tools tend to be a horizontal so network element to network element.