Link Names in Upgraded Systems

On freshly installed systems, datalinks are automatically named net0 through netN-1, where N represents the total number of network devices.

On the contrary, if you upgrade from another Oracle Solaris 11 release, the datalinks retain their names that were established prior to the upgrade. These names are either the default hardware-based names or customized names that the administrator assigned to the datalinks before the upgrade. Further, on these upgraded systems, new network devices that are subsequently added also retain the default hardware-based names rather than receive generic names. This behavior for upgraded systems ensures that no generic names assigned by the OS become mixed with other hardware-based names or customized names assigned by the administrator before the upgrade.

You can replace both hardware-based names as well as OS-supplied link names with other names that you prefer to use. Typically, the default link names that OS assigns suffice for creating the system's network configuration. However, consider the following information before making changes to link names.

Replacing Hardware-Based Link Names

If your system's links have hardware-based names, rename these links with at least generic names. If you retain the hardware-based names, confusion might arise later when these physical devices are removed or replaced.

For example, you retain the link name bge0 that is associated with the device bge0. All link configurations are performed by referring to the link name. Later, you might replace the NIC bge with the NIC e1000g. To reapply the former device's link configuration to the new NIC e1000g0, you would need to reassign the link name bge0 to e1000g0. The combination of a hardware-based link name bge0 with a different associated NIC e1000g0 can cause confusion. By using names that are not hardware-based, you can better distinguish the links from the associated devices.

Caution About Changing Link Names

Although replacing hardware-based link names is a best practice, you must still plan carefully before you rename links. Changing a device's link name does not automatically propagate the new name to all existing associated configurations. The following examples illustrate the risks when you change link names:

• Some rules in an IP Filter configuration apply to specific links. When you change a link's name, the filter rules continue to refer to the link's original name. Consequently, these rules no longer behave as expected after you rename the link. You need to adjust the filter rules to apply to the link by using the new link name.

• Consider the possibility of exporting network configuration information. As previously explained, by using the default net# names provided by the OS, you can migrate zones and easily export network configuration to another system. If the target system's network devices are named with generic names such as net0, net1, and so on, then the zone simply inherits the network configuration of the datalink whose name matches the datalink assigned to the zone.

Thus, as a general rule, do not rename datalinks randomly. When renaming datalinks, ensure that all of the link's associated configurations continue to apply after the link name is changed.

Some of the configurations that might be affected by renaming links are as follows:

• IP Filter rules

• IP configurations that are specified by using the ipadm command

• Oracle Solaris 11 zones

• autopush configuration

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  Note -  No changes are required in the autopush configuration when you rename links. However, you must be aware of how the configuration works with the per-link autopush property after the link has been renamed. For more information, see Setting the STREAMS Module on Datalinks.

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Rules for Valid Link Names

When you assign link names, observe the following rules:

• Link names must consist of a string and a physical point of attachment (PPA) number.

• The link name must abide by the following constraints:

  • Names ideally consist of between 3 to 8 characters. However, names can have a maximum of 16 characters.

  • Valid characters for names are alphanumeric (a–z, 0–9) and the underscore (_).

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    Caution  -  Do not use upper case letters on link names.

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• Each datalink must have only one link name at one time.

• Each datalink must have a unique link name within the system.

The function of the link within your network setup can be a useful reference when you assign link names. For example, netmgt0 can be a link that is dedicated to network management. Upstream2 can be the link that connects to the ISP. As a general rule to avoid confusion, do not assign names of known devices to your links.