Preference-based EVPN DF Election

The introduction of the modulo-based Disganate Forwarder (DF) election algorithm, referred to as RFC 7432, is complemented by RFC 8584, which enhances the DF election process with the Highest Random Weight (HRW) algorithm. These two algorithms provide an efficient and automated method for selecting the DF. However, human oversight is necessary in some situations, particularly for maintenance purposes. To address this, the draft-ietf-bess-evpn-pref-df proposal presents a new method for DF selection: preference-based DF. This approach allows for DF elections based on manually configured preferences, thereby enhancing the control granularity of the DF election process.
In our testing, the left-side DUTs were configured to be multihomed without Link Aggregation Control Protocol (LACP). We generated two broadcast streams from each end and received only one copy of the broadcast from the other end, indicating that the DF's essential function operated as expected. Subsequently, we performed a switchover by assigning a higher preference to the non-DF DUT. This switchover also functioned as intended.
Spirent TestCenter was used as the traffic generator for this test.