RFC 7432, "BGP MPLS-Based Ethernet VPN", February 2015Source of RFC: l2vpn (rtg)
Errata ID: 5523
Publication Format(s) : TEXT
Reported By: Krishnamoorthy Arumugham
Date Reported: 2018-10-12
Rejected by: Deborah Brungard
Date Rejected: 2018-10-25
Section 7 says:
Clarifications to following sub-sections: Section 7.1 Section 7.2 Section 7.5
It should say:
Section 7.1: Add below text to the section 7.1 regarding the encoding of MPLS label: "The value of the 20-bit MPLS label is encoded in the high-order 20 bits of the 3 bytes MPLS Label field." Section 7.2: Add below text to the section 7.2 regarding the encoding of both the MPLS label fields: "The value of the 20-bit MPLS label is encoded in the high-order 20 bits of the 3 bytes MPLS Label field for both MPLS Label1 and MPLS Label2." Section 7.5: Add below text to the section 7.5 regarding the encoding of ESI Label fields: "The value of the 20-bit MPLS label is encoded in the high-order 20 bits of the ESI Label field."
MPLS label is a 20-bit value and is stored in a 3 bytes field in a packet. The 20-bit MPLS label value is generally stored in higher order 20 bits of the 3 byte label field. The exact encoding to be followed for storing MPLS label values are not explicitly mentioned in the RFC 7432 under section 7.1, 7.2 and 7.5 for different types of EVPN routes. This lead to ambiguity in different implementations. Hence a clarification is required.
The ESI label is required to be a "valid MPLS label value", there is no reason to interpret that it should be different from Label 1 and Label 2. There is nothing technically wrong with what is currently in the RFC.