You can designate WhatsUp Gold Discovery address exceptions (SETTINGS > Discovery Settings > IP/MAC Address Exceptions) for cases where Discovery detects devices on your network that share an identical network or hardware address. Adding an address exception gives WhatsUp Gold Discovery the hint it needs to recognize host boundaries when it scans environments that use either non-standard hardware addressing or non-standard network configuration (or both).

提示: Firewalls, routers, and layer 3 switches deployed in a high-availability configuration will often use shared IP addresses.

Background

By default, WhatsUp Gold Discovery uses network or hardware addressing to identify the 'uniqueness' of devices. Shared addressing can occur in special network architectures or topologies and is normally restricted to LANs such as high-availability environments, network load balancing, and virtualization schemes. In these scenarios, IP addresses or MAC addresses can be unreliable predictors of device or host boundaries. After you apply a Discovery address exception and restart the Discovery Service, all devices using designated addresses under this exception will be visible via the Discovery Map and Discovery List.

Actions

Add (IP Address). Create new IP address exception. Subnet ranges supported.

Add (MAC Address). Create new MAC address exception. Prefix matching supported.

Edit. Modify exception. Built-in exceptions (IANA/IETF reserved/restricted addresses, for example) cannot be modified.

Delete. Delete exception.

提示: Before you delete an IP address exception, copy the IP address value. You can re-use this value, including CIDR notation if applicable, for the Discovery Scan.

Typical Workflow When Managing Devices Using Duplicate Addressing

A typical workflow for managing and monitoring devices using shared addressing scheme is:

1.

Identify

Identify addresses or segments you want to apply address exceptions to. Typical scenarios include:

  • Missing devices. After discovering categories of devices mentioned in the topic titled Typical Uses of Shared Addressing, you notice fewer devices displayed on the map/list than you expected.
  • Merged device records. A device such as a gateway or firewall deployed in a high availability configuration is merged with its peer(s) as shown in the Device Merge Decision Information.
  • General investigation. You can apply exceptions on small segments such as those meeting the characteristics outlined in Typical Uses of Shared Addressing as a way to detect NAT activity, network bridging, and more.

2.

Start Fresh

If you already scanned your network, it is best practice to start fresh —delete any devices from WhatsUp Gold that might have been merged due to shared addressing schemes.

3.

Add Exception

Apply exceptions for these addresses either individually, as a subnet range, or vendor prefix (MAC).

4.

Restart and Rescan

Restart the discovery service to make your exceptions active and re-run discovery.

After you apply your address exceptions, and after the Discovery service is restarted and re-reads its configuration, you will need to rescan the network, network segment, or address of interest to see the results of your changes.

5.

Add Monitoring

After you have scanned your network, you can determine if any new devices found (as a result of address exception rules) should be added to the monitored network and count against your licensing.

註: To apply address exceptions to the WhatsUp Gold Discovery configuration, you need to restart the Discovery service.

Rescan Guidelines

Use these scan/rescan guidelines after making changes to the table of IP address exceptions:

  • Scan the same IP range. If you suspect shared address use is limited to a specific subnet or range, re-Discover the range you added an address exception for. For example, this is the best approach if you are looking for duplicates between address pools allocated by one-or-more wireless controllers, ranges that you know where VMs can be typically found, or any of the other scenarios where IP duplication is likely to occur.
  • Apply scan to all monitored devices. If you want to apply changes only to monitored devices, select all devices from the MY NETWORK List, and choose Rescan from the Device Management Actions menu.

Rescan guidelines for MAC address exceptions:

  • Scan specific subnets or IP ranges. For example, if you added an exception for the VMware vendor MAC prefix (00:50:56), you can target a rescan on the subnet or IP address range where you know VMware VMs are running.
  • Sweep the network. If you are taking a 'cast-a-wide-net' approach and you are just looking for a misconfigured, masquerading, or other unexpected use of addressing, you can widen scan coverage.