Support for software running on RHEL/CentOS 6

VTM-43879 Version 20.3 was the last release to support 2.6.32-based kernels or glibc 2.12. Versions from 21.1 onwards require kernel version 3.10 or later, and glibc 2.17 or later, as described in Product Compatibility.

In particular, this means that it is not possible to install version 21.1 or later on a RHEL/CentOS 6 system, or to upgrade an existing Traffic Manager instance on RHEL/CentOS 6 to version 21.1 or later.