# RFC Errata

#### RFC 8584, "Framework for Ethernet VPN Designated Forwarder Election Extensibility", April 2019

Source of RFC: bess (rtg)
Errata ID: 7811

**Status: Reported
Type: Technical
Publication Format(s) : TEXT**

Reported By: Luc André Burdet

Date Reported: 2024-02-15

Section 3.2 says:

Where: o DF(V) is defined to be the address Si (index i) for which Weight(V, Es, Si) is the highest; 0 <= i < N-1. o BDF(V) is defined as that PE with address Sk for which the computed Weight is the next highest after the Weight of the DF. j is the running index from 0 to N-1; i and k are selected values.

It should say:

Where: o DF(V) is defined to be the address Si (index i) for which Weight(V, Es, Si) is the highest; 0 <= i <= N-1. o BDF(V) is defined as that PE with address Sk for which the computed Weight is the next highest after the Weight of the DF. j is the running index from 0 to N-1; i and k are selected values.

Notes:

Paul Kyzivat raised a point while reviewing EVPN Port-Active draft, that really points to a possible algorithm errata in RFC8584 ;

Basically, when evaluating the DF for HRW,

> * DF(Es) is defined to be the address Si (index i) for which

> Weight(Es, Si) is the highest; 0 <= i < N-1.

Here,

if N=1, no remotes: 0 <= i < 0 -- ERROR

if N=2, 1 peer: 0 <= i < 1 -> possible values are only 0 meaning index 1 (the peer)’s weight is not considered.

Logically, this should be 0 <= i <= N-1 or 0 <= i < N ?