Creating or editing link-local subnets in a network fails with the error: "The configured subnet cannot be link-local, loopback, multicast, etc"

Products

• VMware Avi Load Balancer

Issue/Introduction

• This error occurs due to a configuration check that disallows the use of "link-local address" ranges when setting up network subnets.
• Link-local addresses are meant for communication within a local network segment, and they are not routable across the broader internet.
  • IPv4 Link-local addresses fall within the 169.254.0.0/16 range.
  • IPv6 Link-local addresses fall within the fe80::/10 range.
• The introduction of a check to disallow these link-local addresses was made in version 30.2.x and 31.x.
• When you try to configure a new network or if the network profile is configured previously (older versions) within one of these reserved ranges (link-local, loopback, multicast, etc.), users will encounter the error "The configured subnet cannot be link-local, loopback, multicast, etc."
• This check was put in place to prevent network misconfigurations, as link-local addresses are reserved for special uses like local communications and cannot be used for routable networks.

Environment

• Avi Load Balancer 30.2.x and 31.1.1

Resolution

• The issue was identified as a restriction that disallowed the use of link-local address ranges for network configurations. However, it was later found that certain customers relied on these address ranges for their production environments.
• As part of the resolution, the check preventing link-local address usage is removed from the must-check section of the configuration in newer versions. The fix is implemented in the following releases:
  • 31.2.1
  • 31.1.2
  • 30.2.3
  • 30.2.2-2p3 and above

Additional Information

NOTE:

• While the restriction has been lifted, it’s important to ensure that link-local addresses are being used appropriately, as they are typically intended for local communication and cannot be routed beyond the local network segment.