What is the maximum number of interface aliases supported in Red Hat Enterprise Linux?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 9
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 5

Issue

  • How many network interfaces aliases does Red Hat Enterprise Linux support?
  • What is the maximum number of interface aliases I can use on Red Hat Enterprise Linux?

Resolution

There is no practical limit.

Root Cause

In Linux kernel 2.2 there was a limit of 255 interfaces.

In modern Linux kernels, interfaces and IP addresses are implemented as a linked list, removing any hard limit of these items.

You can add IP addresses until you run out of system RAM from allocating the (very tiny) kernel data structures. This is kernel function __inet_insert_ifa()

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