Difference between EMS and NMS

In telecom industry, these two terms EMS aka Element Management System and NMS aka Network Management System are used interchangeably most often. But, these two terminologies do differ in their true meaning and should be used wisely. Below are the definitions of EMS and NMS which clearly states the differences between these two.

Element Management System (EMS)

  • An element management system (EMS) manages one or more of a specific type of network elements (NEs).
  • Using an EMS a user can manage all the features of each NE individually, but not the communication between NEs. Communication between NEs is managed by the network management system (NMS).
  • One or more management interfaces are exposed by NEs that the EMS uses to communicate with and to manage them. These management interfaces use a variety of protocols such as SNMP, TL1, CLI, XML, and CORBA.


Network Management System (NMS)

  • A network management system is a combination of hardware and software used to monitor and administer a network.
  • Network management refers to the maintenance and administration of large scale computer networks at the top level. Network management is the execution of the set of functions required for controlling, planning, allocating, deploying, coordinating and monitoring the resources of a network including performing functions such as fault management, configuration management, accounting management, performance management, security management and bandwidth management.
  • A large number of protocols exist to support network and network device management. Common protocols are SNMP, TL1 and JMX etc.



The network elements in the network each communicate with their respective EMS. The NE-specific EMSs communicate to a higher level NMS that provide integrated multivendor network management. This is depicted in the diagram below:

Network Management Hierarchy

Only the EMS is exposed to complete management information content of all the NEs in its domain. It is the sole mediator of this information and the control of the NEs to the Network Management Layer

Hope you find this information useful. Please leave your footprints in comments section below for any feedback, queries or suggestions…!!

  1. Hi,

    The post is realy good and useful. I need a small clarification, can you explain this.

    Vendor A EMS will manage NE’s from Vendor A, similarly Vendor B and otherVendor EMS’s manage NE from their Manaufactuers. The Information given by a NE from Vendor A could be understood only by the Vendor A EMS, similarly this applies for other EMS’s. So all these vendor specific EMS’s will forward the information which they collected from their NE’s to the NMS in a Common Format which the NMs can understand and the NMS will communicate with the Vendor EMS’s in a genric way, which the Vendor EMS’s translate to the format which the vendor specific NE’s can understand?

    Thanks,
    Guru

  2. Hi Guru,

    Thank you for the positive feedback :)

    Now coming to your query, you are absolutely correct till here “Vendor A EMS will manage NE’s from Vendor A, similarly Vendor B and otherVendor EMS’s manage NE from their Manaufactuers. The Information given by a NE from Vendor A could be understood only by the Vendor A EMS, similarly this applies for other EMS’s. So all these vendor specific EMS’s will forward the information which they collected from their NE’s to the NMS”

    Having a common format between different vendor EMS’s and NMS is the best case scenario. Practically, it is difficult (of course possible) to achieve the same, many a times the reason being that we deal with legacy systems. For instance EMS A exposes Corba interface and EMS B exposes SNMP interface, in this case, NMS should expose both these interfaces to southbound i.e. EMSs. To achieve a common format, we can introduce a mediation layer between NMS and EMSs that can take care of these protocols from southbound and provide data in same format to north bound.

    Hope this clarifies your doubt. Please let us know for further queries :)

    • Hi,

      All above discussion is really more informative, Thanks :) .

      I have a doubt about the sentence -”Using an EMS a user can manage all the features of each NE individually, but not the communication between NEs. Communication between NEs is managed by the network management system (NMS).”

      With respect to above statement, i am confused, Is the Communication between NEs is not possible by EMS eventhough all NEs are specific to that particular EMS? If i am not wrong, All NEs managed by NMS through EMS itself right?. NMS send the request to the EMS then EMS send the request to NEs and response will come back to EMS and EMS will in turn send response back to the NMS. Please correct me if am wrong.

  3. Hi,

    First off, thanks for your fantastic explanation.

    I need a small clarification on the point:
    “Using an EMS a user can manage all the features of each NE individually, but not the communication between NEs. Communication between NEs is managed by the network management system (NMS).”

    I did interpret that you are saying the communication between NEs of the *same* vendor also cannot be managed by EMS, but NMS only can do that. If my understanding is correct, can you please explain why it is not possible for the EMS to manage the NEs communication when all belong to same vendor?

    Many Thanks!
    MPk30

  4. Thanks for wonderful explanation.what about the careers in this EMS or NMS technology.how much will be the package for freshers.

  5. Dear All,

    I worded on multi vendor EMS and NMS in RCOMM. There what knowledge i gained on these two entities are as follows:

    1. NE – the lowest entity like MUX
    2. EMS/EC-1 : This is the mediator b/w NE & NMS.
    3. NMS- This is second highest apllication which helps to monitor a big span of n/w.

    *This manages multiple EMS. NMS can directly manages NEs also*

    By saying that it raises question that then “What is the difference b/w EMS & NMS?”
    Ans: Broadly there is no difference we can use both or time we can have two separate applications!
    However, still there is a tiny theoretical difference b/w these two which is one can perform and another cant.
    By using NMS- we can do PROVISIONING which is not possible in EMS.
    Take an example:
    we have two Nortal EMS/OMEA one have all MUX belongs to Delhi region and one have all nodes belongs to Noida.
    Suppose we want to create a TRAIL from Node-1 to Node-5 (all belongs to same Delhi region)
    All we can do using EMS login to each node from 1 to 5 and create XCs which later form a TRAIL.
    Similarly if we want to create a TRAIL which starts from Delhi CP and terminated at Noida -62.
    - In this specific case one can login to EMS-1 (Delhi) and create XCs and further login to EMS-2(Noida) and do the same.
    This create lots of login and log out activity and tiresome also.

    * In such cases we need NMS, which is directly or indirectly connected to EMS-1 & EMS-2.
    All you need to do is login one application(NMS) and do logical XCs.

    ………………………………………

    I have never seen one vendor EMS communicating with another vendor NMS this due to the communication protocol arch difference.These are propriety applications so they have designed in a manner that they can communicate with their applications only.

    But we have applications which provides cross platform comms.

    OSS – In RCOM we have Clarity

    OSS – provides cross platform comm.

    In a company where we have Nortel,Marconi,fibcom NMS/EMS

    But i am V P & I just want to check the status of my whole n.w while login to single application.
    This facility I get by using OSS which can comm with Nortel, Marconi,Fibcom NMS/EMS directly.

    So what is the difference b/w NMS & OSS?
    Ans: Again no difference broadly. If a NMS is so powerful that can comm with another NMS/EMS. In that can it act as OSS.

    ……………………………………………….

    Coming back to the question gentleman has asked “What does it mean by EMS cant control comm b/w NEs like that”
    Ans: EMS is directly connected to node and we do all trouble shooting and OAM functions. As I explain above creating DIRECT links b/w node physically connected node after checking the trace and all is possible thorough using NMS only but not by EMS.

  6. Thanks for these explanation. so with above explanation my understanding is the logical connections between two nodes which are belongs to two different EMS can be done using NMS only. But why cont we do the logical connections of the two nodes which are physically connected of the same EMS(similar nodes which are under the same EMS)?

    Can you please explain this?

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