Managing NerveCenter - Managing Node Data - Filtering Nodes - Filtering Using a Node's System Object Identifier -
Filtering Nodes      Processing Traps from Unknown Nodes

Filtering Using a Node's System Object Identifier

NerveCenter allows you to monitor managed nodes according to their particular system object identifiers (OIDs).

A node's System Object ID is an SNMP MIB-II object in the system group. It identifies the SNMP agent software running on the device. It is, however, commonly used to identify the type and vendor of the device because a particular vendor's agent usually runs on that vendor's devices.

 
  To filter using a node's system object identifier:

1. Open NerveCenter Administrator and connect to the appropriate NerveCenter Server.

   See the section Connecting Administrator to a NerveCenter Server on page 38.

2. Select the Node Source tab.

   NerveCenter displays the Node Source tab.

   

3. In the System Object Ids field, type the name of the system OID wanted.

   If this field is left blank, NerveCenter will not filter using a node's system OID.

4. To enter multiple OIDs, separate each with a space.

   NerveCenter will monitor any node that matches at least one of the OID in the list.

   For example, an administrator may want to restrict NerveCenter to nodes running SNMP agents from either Cisco or Hewlett-Packard nodes by typing the following:

   1.3.6.1.4.1.9 1.3.6.1.4.1.11

   Any device with an OID matching either of these numbers will be included in the NerveCenter nodes database.

5. Select Save.

   The NerveCenter Server adds the new OID filter. It also closes and opens a new connection with the platform adapter. NerveCenter automatically resynchronizes with your network management platform's database.

New nodes will be added. Any node that is marked Autodelete (the default) will be deleted.

Filtering nodes using a Node's IP Address

In addition to filtering nodes by OIDs and capabilities, NerveCenter allows you to filter out all nodes that do not belong to one or more subnets. NerveCenter determines the subnet by combining a specific IP address with a subnet mask. NerveCenter can filter by subnets of both Class B and Class C networks. In Class B networks, the first two octets specify the network while in Class C networks the first three octets identify the network.

Sample Subnet Filters and Their Results for a Class C Network and Sample Subnet Filters and Their Results for a Class B Network illustrate some filter configurations and their results:

Sample Subnet Filters and Their Results for a Class C Network

In addition to filtering out all but an entire subnet, NerveCenter allows you to exclude a specific node or range of nodes within the remaining subnet.

Sample Subnet Filters with Exclusions and Their Results illustrates some filter configurations with exclusions and their results.:

Sample Subnet Filters with Exclusions and Their Results

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   You can filter nodes that have been discovered by NerveCenter, provided by the platform node source, or imported from a node file.

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NerveCenter can determine automatically or manually subnet criteria used to filter nodes by IP address.

 
  To configure NerveCenter to determine subnet criteria automatically:

1. Open NerveCenter Administrator and connect to the appropriate NerveCenter Server.

   See the section Connecting Administrator to a NerveCenter Server on page 38.

2. Select the IP Filters tab.

   The IP Filters tab is displayed.

   

3. In the Method area, select Automatic.

   Setting the method to automatic tells NerveCenter to ignore any address filters you enter and use instead the server's masks as a filter. NerveCenter calculates the subnet address and mask using the IP address and mask of each network interface card on the server.

4. Select Save.

NerveCenter will now automatically use the server's masks as a filter.

 
  To set the subnet criteria manually:

1. Open NerveCenter Administrator and connect to the appropriate NerveCenter Server.

   See the section Connecting Administrator to a NerveCenter Server on page 38.

2. Select the IP Filters tab.

   The IP Filters tab is displayed.

   

3. In the Method area, select Manual.

   When the method is set to manual, NerveCenter will only use the subnet addresses listed in IP Address Filters area. If the IP Address Filters list is empty, NerveCenter ignores a node's subnet when determining if the node will be part of the node database.

4. In the Subnet Address field, type the appropriate subnet. In the Mask Address field, type the appropriate subnet mask.

   A node's subnet address combines the node's IP address with the subnet mask.

5. In the Exclusion List field, enter all the nodes you want excluded from the subnet address. To exclude more than one node, separate each number with a comma without a space. To exclude a continuous range of nodes, use a hyphen to separate the minimum and maximum number by a hyphen.

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      Once you have added a node using the IPSweep behavior model, you cannot use an IP exclusion to delete it from the database. Once the node is in the database, the IP exclusion filter is not applied to it. The IP exclusion applies only to new nodes discovered after the filter is established.

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6. Select Add.

   The subnet address and mask address will be added to the IP Address Filters list.

   

7. Select Save.
8. To filter by additional IP addresses and masks, repeat steps 4 and 7.

NerveCenter monitors any address falling within the subnet and not excluded by the filter.