How does snmp discovery work

Then the objects are added into the database. If the object is already added, the Properties of the object is updated with the Properties that are currently discovered for this device. When a router is discovered by NMS, the discovery engine will identify the list of interfaces in the router and the networks to which these interfaces belong to.

Switch discovery is part of the default NMS discovery engine. Switch Discovery is performed by SwitchDiscoveryFilter. To get the list of ports and their properties in the switch you can perform the following queries.

Queries to get the IfSpeed and IfIndex are sent to the agent with appropriate portindex values appended at the last of the oids. The port objects are added into the database with the properties collected using the above mentioned queries. Note : The Switch discovery performed here is a general implementation. In the past, only very large companies and organizations with equally large IT staff had to deal with network management at a massive scale, but times have changed. Today, even small companies with just a few employees rely on complex networks, and they need every bit of help they can get to manage them, which is where Simple Network Management Protocol SNMP comes in.

Created in to provide a reliable way for different devices on a network to share information with one another, SNMP is an Internet Standard protocol for collecting and organizing information about managed devices on IP networks. The protocol is supported by servers, workstations, printers, routers, switches, hubs, scanners, and internet of things IoT devices, allowing them to communicate even if they are made by different companies and run different software.

Essentially, SNMP provides a common language that various network monitoring tools can use to determine the status of network devices in real time, keep track of changes to the network, monitor network performance, or identify devices, just to give a few examples. Routers, switches, and sometimes even servers enable SNMP by default, but the same cannot be said about workstations.

Windows 10 users can, however, enable SNMP manually with just a few clicks. The exact details of the process depend on which version of SNMP is used. By far the easiest way how to initiate the SNMP network discovery process is a network discovery and management tool such as Network Inventory Advisor.

This free-to-try software application can collect all relevant data on all network devices, including routers, servers, workstations, and even non-IT assets, and display the collected information in the form of customizable reports.

Thanks to its automated network audits, which can scan hundreds and thousands of connected devices in a matter of minutes, Network Inventory Advisor provides the visibility companies of all sizes need to grow their networks in the most optimal manner. SNMP has been described as both cool and evil. For the snmp discover process , a router is a device, defined as a group of hosts, one for each network interface. A router allows the routing of IP packet between these interfaces.

The snmp discover process will manage a router as individual hosts. This object is used and managed by another process of LoriotPro. The screen below shows you a router built from a group of two hosts with the reference RouterID Remark: Refer to the chapter concerning the Directory router object from more information about router creation. There are few algorithms to use for a complete discover of the network devices.

From that, it builds the IP topology. This method is efficient because it is not necessary to request all devices connected to the network in order to know that they are present and active. Of course a remote host will only be discovered if it had already exchanged packets with its default router, else it would not be seen. The reading of the router ARP table gives only volatile information, the table is flush every 4 hours. A host configured for not responding to Ping request or any other IP request will be discover anyway.

However, if the remote device does not leave any trace in he router it will not be discovered. Discover principle working example. In this context, one of the C router interfaces is known, as well as its SNMP read community, the snmp discover process will find out in two-step the topology and the devices connected to the network.

Beside the network is discovered in a sequential manner regarding the defined setting and in the reverse order of the discovered hosts. The DSNMP program, which is the kernel of the Directory, manages all resources of host type in a chained structure list.

A scan cycle consists of calling the first host of this list, using its conFigure d setting and if it succeeds, to do all schedule SNMP requests to it. The next host in the list is treated the same way and so on, up to the end of the list.

In case of new discovered hosts, the snmp discover process asks to the DSNMP process to creat a new entry in the chained list and thus save the new host object and its settings. At the next Discover cycle the newly discovered host will be questioned first. Discover process algorithm. The snmp discover process is fully configurable and could be fine tune to your expectation. The configuration windows is accessible from the main menu:. ConFigure option of the main menu.

Discover process window. Remark: Remember, the snmp discover process works as a background task of the LoriotPro kernel and this window is only a configuration window. To perform the scanning cycles, the snmp discover process uses the hosts settings stored in the Directory and a few others allowing a more precise analysis. The Enable Discover Process option allows you to do periodic discover at regular intervals. The setting Discover Process Running Interval defines the time between each discover cycle.

Warning: If you check the "Enable Discover Process" option, an information window reminds you that you will send SNMP requests to all of your network hosts and that links will be used. Activating the snmp discover process could open these links and generate unwanted costs.

Warning window. If you answer Yes, you will be able to conFigure the discover cycle occurrences. Remark: In our preceding example, three cycles were necessary to discover the network. If the discover cycle frequency is set at seconds, it will take at least secondes to discover the network. If the frequency used is lower than the time needed to do a completediscover, the snmp discover process will run continuously. The process automatically switches to the SNMP version and selects the right read community of the current scanned host.

By default the SNMP version 1 is used when the process interrogates a new host but version 2c request could also be use in case of no response in version 1. Remark: By default the snmp discover process creates new discovered networks under the root World of the Directory tree.

It is possible to modify this option and locate the Networks in a container of your choice. To do that, select the desired container in the tree and use the menu option 'Set Home Container' of the sub menu 'Discover Anchor '. Warning: This option is automatically set to root each time you restart Loriotpro. As we already mention, the snmp discover process reads SNMP tables in the host in order to build its vision of the network topology.

Scan the IpRouteEntry table and gather information iproutedest andt iproutemask for building network objects in the Directory. Warning: If pour router is connected to an external network Extranet or Internet it could be possible that you will see unneeded networks. It is possible to limit the scan range to a set of IP addresses.

Check box 'Set and use IP range'. In the example below, only hosts in the Directory having addresses between IP address range configuration window. Warning: This range should be contiguous. The text displayed in the information zone reminds you that an IP address range is used. During the scanning cycle, the text informs you about the current scanned address. The IP Expert uses in that case script programs. In the Discover Process configuration window, you can set up few option for activating the IP Expert process.

The scan is performed only if the Network Object property settings allow it. In the Network Object property be sure that the "Make a new scan of this network at the next discover process" is checked. The scan is performed only if the Host Object property settings allow it.

See example below. Assign host parameters from IP Expert Informations Extended Edition : If the IP expert use discover strategies based on script the host parameters can be assigned directly by script functions. This options allows this features only available with the Extended Edition of LoriotPro.