Overview

Three overlapping-IP-address capabilities are available to the IP Manager:

• IP tagging

• Unmanage admin down

• IP management domain policy-based or source routing

  Overlapping IP address is described in IP address types and definitions, IP tagging is described in IP tagging feature, and Unmanage admin down is described in Unmanage admin down feature. IP management domain policy-based or source routing is described in this appendix.

Table 1. IP address types and definitions

IP address type	Description
Overlapping IP address 1	In a centrally managed configuration in which an ISP manages the private IP networks of different clients, overlapping IP addresses come into existence when the private IP networks employ identically-numbered IP address spaces. An overlapping IP address may be a management IP address or a non-management IP address.
Management IP address	An IP address that is bound to a device’s SNMP agent. The IP Manager uses a device’s management IP address and ICMP and SNMP polling to discover information about the device and to monitor the device after it is discovered.
Non-management IP address	An IP address that is not bound to a device’s SNMP agent. A non-management IP address is associated with a physical interface of a device. For a non-management IP address that is part of a discovered device, and assuming that one or more routes exist between the host that is running the IP Manager and the non-management IP address, the IP Manager will use ICMP polling to monitor the address.
1  Described in detail in the IP Manager Concepts Guide.

Table 2. IP tagging feature

Topic	Description
Introduction	IP tagging 1 and IP tag filters enable the IP Manager to create IP objects in its modeled topology that represent overlapping IP addresses.
Unmanaged IPs	By default, an IP tag filter sets all IP objects that are created for overlapping IP addresses to “unmanaged.”
Monitoring overlapping IPs	The IP Manager monitors the status of the overlapping IP addresses by periodically sending ICMP and SNMP requests to the devices on which the overlapping IP addresses were discovered. Even for a pair of overlapping IP addresses that are reachable, the IP Manager will not be able to monitor them directly because it will not be able to determine which of the devices that are associated with those IP addresses is responding to the ICMP and/or SNMP polls.
1  Described in detail in the IP Manager Concepts Guide .

Table 3. Unmanage admin down feature

Topic	Description
Introduction	Unmanage admin down 1 is an alternative to using the IP tagging feature to discover overlapping IP addresses. When Unmanage admin down is enabled, the IP Manager will not discover any IP address that is associated with an administratively down interface.
Purpose	This discovery behavior allows for a situation in which two devices are sharing a management IP address for the following reason: The currently active device is to be replaced by the administratively down device. In this situation, the IP Manager will discover and create an IP object for the currently active device, but will not discover an IP object for the administratively down device. When the replacement device becomes active, and the currently active device becomes administratively down, the polling will continue.
1  Described in detail in the IP Manager Concepts Guide.

The IP management domain policy-based or source routing capability enables two or more IP Managers that are running on the same host system to poll simultaneously the two or more instances of an overlapping IP address.