FAQs on NMS

Do you want to crack interview on NMS? Well, you are at right place then J

FAQs on NMS (mainly NMS with SNMP):-

1. What is NMS? => It’s a Network Management system which  manages the network nodes like routers, switches, access nodes, servers, hosts and many more. NMS is mainly concerned with how the network nodes are tied up together and hence manage them in terms of networks rather than managing individual nodes. NMS is 3^rd layer in TMN architecture.
2. What are the most common protocols used by NMS to communicate with the nodes? =>SNMP,CORBA,TL1,SSH,Telnet e.tc
3. Which transport layer protocol is used by SNMP? What are the ports used? => SNMP normally uses UDP protocol. NMS uses port 161 to communicate with the agent and listens to port 162 for the traps sent by the agents.
4. How the reliability is achieved in NMS with SNMP? => As UDP is unreliable protocol, there may be chance of traps getting lost. Hence many NMS uses polling to retrieve the missed traps.
5. When NMS system is using only SNMPV2, how can you manage a agent which is using only SNMPV1? => NMS uses one proxy which converts SNMPV2 messages to SNMPV1 messages to communicate with the agent. If NMS is sending getbulk request then proxy converts them to multiple getnext requests and process to the agent.
6. I have three different agents which uses different SNMP versions. How do you manage them with a single NMS? => We can have multilingual NMS which can talk to the agent with any versions.
7. What feature NMS uses to populate the agents? => NMS uses Discovery feature to populate the agents in the management systems. First NMS uses ICMP to check the reachability of agents and then SNMP probing to populate the devices.
8. How does NMS perform discovery when the agents aren’t enabled with SNMP/CORBA/TL1 protocols? => We have CLI discovery mechanism which uses SSH/TELNET to perform the discovery in such cases.
9. What mechanism NMS can use when we don’t need to poll certain objects as polling consumes too much bandwidth? => NMS can use differential polling mechanism to poll the objects/classes of the agent. By doing so, we can assign less polling interval for very critical attributes and high polling interval for medium attributes and disable polling for the attributes which needn’t be polled.
10. What is difference between SNMP Traps and Informs? => Traps are unacknowledged, but Informs are acknowledged. Traps are sent from Agent to Manager, but Informs are sent from Manager to manager.

I have many more questions like this; will be updating them when I get time later.