Data Import

If a device hostname or system name is changed by a network administrator, it may affect NetIM. This section describes how to manage these changes.

By default the NetIM adapter priority used for the sysName model attribute is set to an equal value for all adapters. If you have changed the sysName adapter priority settings, and a hostname is changed, you may see duplicate representations of the same physical device in the network model.

When hostnames are changed in your network, NetIM may produce the same device or portions of the device under both names, especially if you are using third-party network management products as data sources. You can recover from this scenario by using the Device Manager to delete the duplicate devices from your model.

As a last resort, you can block import of the device from the adapter that is a source for the device and delete the obsolete device from the database. Use the Device Manager for both operations.

When device names change, any device groups that reference the device by the old name will no longer include the device. The old name will still appear in the device group, but the device no longer shows up in a model when its device group is imported into an analysis software client. If the device is a member of any blocked import groups, data import from the blocked source will resume for the device.

NetIM imposes few restrictions on the names given to devices in your network. Device names may contain spaces, slashes, backslashes, and punctuation marks. Some unusual combinations that are not currently supported are listed below.

Note the following restrictions:

• If the hostname of a device comprises a series of dots (one or more), no splitting is performed on the name to separate it into host.domain. If the hostname is ....foo.com, the device is imported to NetIM as ellipses (...); the domain is ignored.

• Cisco devices with hostnames longer than 29 characters are imported as 2 devices.

• Devices with a hostname ending in a backslash character (\) are imported into the network model with \ missing from the name.

• Devices with hostnames that contain XML special character elements either fail to be imported or are imported incorrectly. Character strings such as “>” and “<” will be converted to “>” and “<” respectively. Other XML elements may cause data import problems.

Interface descriptions that contain XML special character elements fail to be imported or are imported incorrectly. Character strings such as “>” and “<” will be converted to “>” and “<” respectively. Other XML elements may cause data import problems.

Duplication of IP addresses in network data may interfere with NetIM’s ability to correctly merge objects and infer connections. There may be a valid reason why IP addresses are duplicated in your network. There may also be instances in which duplicate IP addresses are being reported by the device operating system either as intended behavior for a particular configuration or as a result of a software problem.

• For the purposes of link inference, if an interface is administratively down, the interface will not be considered as a link endpoint. However, if there are duplicate IP addresses for interfaces, and these interfaces are not administratively down, connections may not be inferred correctly. Consult the Duplicate IP Address report to determine if this may be problem.

Juniper ERX devices report the same IP address on interfaces that are configured on different virtual routers. For example:

virtual-router FOO
interface FastEthernet 1/0.1
ip address 10.1.1.1 255.255.255.0
!
virtual-router BAR
interface FastEthernet 1/0.2
ip address 10.1.1.1 255.255.255.0
!

This has implications for both interface merging and link inference. An IP Address Merge exclusions file can be used to prevent merging based on the duplicate IP address; however link inference will still infer links using this address.

Some vendor devices report duplicate MAC addresses on interfaces. This may interfere with NetIM’s ability to correctly merge objects and infer connections.

When the CAM engine is enabled in Link and Connection Inference, MAC address forwarding tables are used to infer connections between Layer-2 devices. Duplicated MAC Addresses may lead to inference of extra links. Consult the Duplicate MAC Address report to determine if this may be a problem.