Routing control functions (RCF) is a new language, a different way of policy definition and application in a programmatic fashion (https://www.arista.com/en/support/toi/eos-4-27-2f/15102-routing-control-functions-language-and-configuration). EOS Application Programmable Interface (eAPI) is another means whereby commands are sent to the switch (i.e. aside from the switch’s command-line interface - CLI which has been the norm), which can be executed through various methods like web interface, shell or a program/script.

This feature introduces a way for IS-IS to advertise its IP reachability and SID for loopback interfaces only when routes matching an RCF function are present. One example use-case is to use IS-IS Segment Routing to attract traffic to a router only when routes towards the ultimate destination are present.

This document describes a new CLI command to help debug how and why policy permits and denies paths. The aim of this CLI command is for the user to debug a route map or RCF (Routing Control Functions) function by specifying as input a prefix for which BGP has reachability for, either via a BGP peer or a redistribute source.

Routing control functions (RCF) is a language that can be used to express route filtering and attribute modification logic in a powerful and programmatic fashion.

Routing Control Functions (RCF) is a language that can express route filtering and attribute modification logic in a powerful and programmatic fashion.The document covers: Configurations of a RCF function for BGP points of application

Routing Control Functions (RCF) is a language that can be used to express route filtering and attribute modification logic in a powerful and programmatic fashion.

Routing control functions (RCF) is a language that can be used to express route filtering and attribute modification logic in a powerful and programmatic fashion.

Routing control functions (RCF) is a language that can be used to express route filtering and attribute modification logic in a powerful and programmatic fashion. 

Routing Control Functions (RCF) is a language that can be used to express route filtering and attribute modification logic in a powerful and programmatic fashion.

In EOS, BGP creates different update groups based on the outbound configuration. Different route maps or Routing

This feature gives users the ability to use Route Control Functions (RCFs) to create custom policies for deciding which routes with IP next-hops should be programmed into the kernel with fwd* next-hop devices so the associated kernel packets are inserted into the ingress pipeline of hardware forwarding instead of being software-forwarded by the kernel.

In EOS-4.31.2F ipv6 link-local next-hops can now be configured in BGP through RCF (Routing Control Functions). On the advertising BGP agent an ipv6 link-local next-hop is configured on the outbound policy function. The receiving BGP agent reads this link-local next-hop and automatically assigns the interface from which the BGP path was sent.