This chapter describes SR Linux interface types, subinterfaces, and support for Link Aggregation Groups (LAGs). See the “Interfaces” chapter in the SR Linux Configuration Basics Guide for configuration examples.
On the SR Linux, an interface is any physical or logical port through which packets can be sent to or received from other devices.
The SR Linux supports the following interface types:
A LAG, based on the IEEE 802.1ax standard (formerly 802.3ad), increases the bandwidth available between two network devices, depending on the number of links installed. A LAG also provides redundancy if one or more links participating in the LAG fail. All physical links in a LAG combine to form one logical interface.
LAGs can be either statically configured, or formed dynamically with Link Aggregation Control Protocol (LACP). Load sharing is executed in hardware, which provides line rate forwarding for all port types. A LAG consists of ports of the same speed.
On the SR Linux, each type of interface can be subdivided into one or more subinterfaces. A subinterface is a logical channel within its parent interface.
Traffic belonging to one subinterface can be distinguished from traffic belonging to other subinterfaces of the same port using encapsulation methods such as 802.1Q VLAN tags.
While each port can be considered a shared resource of the router that is usable by all network instances, a subinterface can only be associated with one network instance at a time. To move a subinterface from one network instance to another, you must disassociate it from the first network instance before associating it with the second network instance.
You can configure ACL policies to filter IPv4 and/or IPv6 packets entering or leaving a subinterface.
The SR Linux supports policies for assigning traffic on a subinterface to forwarding classes or remarking traffic at egress before it leaves the router. DSCP classifier policies map incoming packets to the appropriate forwarding classes, and DSCP rewrite-rule policies mark outgoing packets with an appropriate DSCP value based on the forwarding class.