Interfaces

In SR Linux, an interface is any physical or logical port through which packets can be sent to or received from other devices. SR Linux supports the following interface types:

  • Loopback

    A loopback interface is a virtual interface that is always up, providing a stable source or destination from which packets can always be originated or received. SR Linux supports up to 256 loopback interfaces system-wide, across all network-instances. Loopback interfaces are named loN, where N is 0 to 255.

  • System

    The system interface is a type of loopback interface that has characteristics that do not apply to regular loopback interfaces:

    • The system interface can be bound to the default network-instance only.

    • The system interface does not support multiple IPv4 addresses or multiple IPv6 addresses.

    • The system interface cannot be administratively disabled. Once configured, it is always up.

    SR Linux supports a single system interface named system0. When the system interface is bound to the default network-instance, and an IPv4 address is configured for it, the IPv4 address is the default local address for multi-hop BGP sessions to IPv4 neighbors established by the default network-instance, and it is the default IPv4 source address for IPv4 VXLAN tunnels established by the default network-instance. The same functionality applies with respect to IPv6 addresses / IPv6 BGP neighbors / IPv6 VXLAN tunnels.

  • Network

    Network interfaces carry transit traffic, as well as originate and terminate control plane traffic and in-band management traffic.

    The physical ports in line cards installed in the SR Linux device are network interfaces. A typical line card has a number of front-panel cages, each accepting a pluggable transceiver. Each transceiver may support a single channel or multiple channels, supporting one Ethernet port or multiple Ethernet ports, depending on the transceiver type and its breakout options.

    In the SR Linux CLI, each network interface has a name that indicates its type and its location in the chassis. The location is specified using the following formats:

    ethernet-slot[/mmda-slot][/connector]/port

    where:

    • slot is a slot number (1 to 9). On 7220 IXR-Dx and 7220 IXR-Hx fixed systems there is only one slot, numbered 1; even though no other slot value is possible, the slot number 1 is still part of the interface name.

    • mda-slot is a number representing the media dependent adapter (MDA) position within the parent card or chassis on devices that support MDA assemblies.

    • connector is a number indicating the front-panel connector/cage to which a breakout cable is connected. It is omitted when there is no breakout configuration.

    • port is a number referring to the front-panel connector/cage to which a non-breakout cable is connected, or else it refers to the channel number (1 to 4) in a breakout configuration.

    For example:

    • Interface ethernet-1/1 can refer to port 1 of a 7220 IXR-Dx system or to port 1 of the 7250 IXR IMM installed in slot 1.

    • Interface ethernet-2/1 refers to port 1 of the 7250 IXR IMM installed in slot 2.

    • Interface ethernet-1/1/1 can refer to breakout port 1 of connector 1 in a 7220 IXR-Dx chassis.

    • Interface ethernet-1/m1/2/4 refers to breakout port 4 of connector 2 on the first MDA of the chassis.

  • Management

    Management interfaces are used for out-of-band management traffic. SR Linux supports a single management interface named mgmt0.

    The mgmt0 interface supports the same functionality and defaults as a network interface, except for the following:

    • Packets sent and received on the mgmt0 interface are processed completely in software.

    • The mgmt0 interface does not support multiple output queues, so there is no output traffic differentiation based on forwarding class.

    • The mgmt0 interface does not support pluggable optics. It is a fixed 10/100/1000-BaseT copper port.

  • Integrated routing and bridging (IRB)

    IRB interfaces enable inter-subnet forwarding. Network-instances of type mac-vrf are associated with a Layer 3 network-instance of type ip-vrf or type default via an IRB interface.

    IRB interfaces are named irbN, where N is 0 to 255. See IRB interfaces.

In SR Linux, each loopback, network, management, and IRB interface can be subdivided into one or more subinterfaces. See Subinterfaces.