Operate and maintain
Documents under this category provide background concepts and procedures for configuring, operating, and maintaining SR Linux software.
- ACL and Policy-based Routing Guide
  This document describes ACL and policy-based routing configuration for the Nokia Service Router Linux (SR Linux).
- Advanced Solutions Guide
  This document describes how to configure advanced solutions for the Nokia Service Router Linux (SR Linux). Advanced solutions are defined as more complex network-level configurations where additional guidance and more detailed procedures may be required.
- CLI Plug-in Guide
  This document describes how to create custom CLI plug-ins, and defines the classes and utility functions used to create them. It also defines how to install, modify, and remove a CLI plug-in.
- Configuration Basics
  This document describes basic configuration for the Nokia Service Router Linux (SR Linux). Examples of commonly used commands are provided.
- gRIBI Guide
  This guide describes configuration details for the gRPC Routing Information Base Interface (gRIBI) feature set used with the Nokia Service Router Linux (SR Linux).
- Interfaces Guide
  This document describes interface configuration for the Nokia Service Router Linux (SR Linux), including subinterfaces, IRB interfaces, LAGs, DHCP relay, and IPv6 router advertisements.
- MPLS Guide
  This guide describes the services and provides configuration examples for the Multiprotocol Label Switching (MPLS) protocol used with the Nokia Service Router Linux (SR Linux).
- Multicast Routing Protocols Guide
  This guide provides an overview of multicast routing concepts and provides configuration examples for Internet Group Management Protocol (IGMP), Multicast Listener Discovery (MLD), and Protocol Independent Multicast (PIM).
- Network Synchronization Guide
  This guide describes the network synchronization features for the Nokia Service Router Linux (SR Linux).
- P4Runtime Guide
  This document describes SR Linux support for P4Runtime and includes procedures for configuring SR Linux to operate with P4Runtime clients.
- Quality of Service Guide for 7220 IXR and 7250 IXR
  This document describes configuration details for the Quality of Service (QoS) feature set used with the Nokia Service Router Linux (SR Linux) on IXR-series platforms.
- Quality of Service Guide for 7730 SXR
  This document describes configuration details for the Quality of Service (QoS) feature set used with the Nokia Service Router Linux (SR Linux) on SXR-series platforms.
- Routing Protocols Guide
  This document describes routing protocol configuration for the Nokia Service Router Linux (SR Linux), including OSPF, IS-IS, and BGP.
- Segment Routing Guide
  This document describes configuration details for the Segment Routing feature set used with the Nokia Service Router Linux (SR Linux).
- System Management Guide
  This document describes the interfaces used with the Nokia Service Router Linux (SR Linux).
- VPN Services Guide
  This document describes basic configuration for Layer 2 and Layer 3 Virtual Private Network service functionality on the Nokia Service Router Linux (SR Linux). It presents examples to configure and implement various protocols and services.

Overview

Programming Protocol-Independent Packet Processors (P4) is an open-source language for programming the data plane on networking devices. P4Runtime is an API for controlling the data plane on devices defined in a P4 program. The P4 language and P4Runtime specification are maintained at p4.org.

The SR Linux eXtensible Data Path (XDP) is not programmed in P4. However, SR Linux is packaged with a fixed P4 program that provides support for marking packets for trapping to a P4Runtime client via PacketIn messages, and transmitting packets from the P4Runtime client to an interface on the device via PacketOut messages. The following fields can be used to mark frames for extraction:

VLAN ID
Ethertype
TTL

This could for example be used to redirect traceroute packets with TTL=0, TTL=1, or TTL=2 to a P4runtime client, so they can be enriched with information that is not visible to the device for the following ACL rules:

TTL=0, IPv4 (ethertype 0x0800)
TTL=1, IPv4 (ethertype 0x0800)
TTL=2, IPv4 (ethertype 0x0800)
TTL=0, IPv6 (ethertype 0x86DD)
TTL=1, IPv6 (ethertype 0x86DD)
TTL=2, IPv6 (ethertype 0x86DD)

Another use case is to use a free ethertype to allow the P4Runtime client to transmit and receive packets on all internal links on all devices in a network as a means of topology discovery.

To accommodate these use cases, the SR Linux runs a grpc_server service that provides the interface between P4Runtime clients and SR Linux.

SR Linux p4rt service

SR Linux supports packet input/output to P4Runtime clients through a grpc_server service named p4rt. This grpc_server process exposes instances of P4Runtime RPCs that P4Runtime clients can connect to, with mandatory arbitration to elect a single P4Runtime client as the primary (see P4Runtime client arbitration).

Instead of running multiple processes, SR Linux runs a single process with multiple sockets.

See Configuring SR Linux for P4Runtime for information about configuring the p4rt grpc_server service.

November 7, 2024