Observed IP ranges reports "0.0.0.1-255.255.255.254"

Products

• VMware vSphere ESXi

Issue/Introduction

The "Observed IP ranges" column in vCenter displays "0.0.0.1-255.255.255.254" for at least one physical adapter (vmnic).

Cause

The "Observed IP ranges" field is populated with a subnet range based on the source IP of broadcast traffic seen by that NIC in the previous 10 minutes. As more broadcast packets are received from IPs in the same network or VLAN, more accurate subnet information can be reported and the listed network range can be narrowed down accordingly.

If the only broadcast packets seen on the NIC in question reports a source IP of 0.0.0.0 however, such as with a DHCP "Discover" packet for instance, the entire usable IP range is listed.

This is caused by there not being enough other broadcast packets being seen on the same VLAN with more specific IP/subnet information that can be used to otherwise limit the subnet.

Resolution

The "Observed IP ranges" field is only a summary of what broadcast packets have been received on that NIC, and has no bearing on the ESXi network logic or behavior. Therefore there should be no impact directly resulting from this state.

That being said, if additional (i.e. not with a 0.0.0.0 source IP) broadcast traffic has been validated to be sent directly to the NIC in question, this output may be an indicator of an underlying network issue as the NIC may not be receiving that traffic, hence the table is not updating accordingly.

Note though that this may also be expected behavior resulting from how the network is configured and communicating, and therefore no change is required in this case.