| Internet-Draft | Abbreviated Title | March 2023 |
| Zhang, et al. | Expires 14 September 2023 | [Page] |
This document describes the IS-IS and OSPF protocol extensions that are required for BIER-TE and RBS with MPLS and non-MPLS encapsulation.¶
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"Bit Index Explicit Replication Traffic Engineering" (BIER-TE) [RFC9262] describes per-packet stateless strict and loose path steered replication and forwarding for "Bit Index Explicit Replication" (BIER, [RFC8279]) packets. It is called BIER Tree Engineering (BIER-TE) and is intended to be used as the path steering mechanism for Traffic Engineering with BIER. RBS [I-D.eckert-bier-rbs] introduces a compact data-structure representation of multicast trees called "Recursive Bitstring Structure" (RBS) and its use for (stateless) forwarding of packets that include this structure in their header.¶
BIER-TE and RBS both use a "bit positions" (BP) for the representation of link or adjacency. [I-D.ietf-bier-te-isis], [I-D.ietf-bier-te-ospf], and [I-D.ietf-bier-te-ospfv3] describe IS-IS, OSPF, OSPFv3 extensions respectively for distributing BitPositions configured on the links in BIER-TE domain.¶
As described in section 2.4 in [RFC9262] and section 5 in [I-D.eckert-bier-rbs], BIER-TE/RBS inherits the encapsulation supporting from BIER unchanged. The encapsulation defined in [RFC8296], which specifies a common header format for both MPLS and non-MPLS networks, though the first 20-bits (referred to as BIFT-id) of the header is an "MPLS Label" in case of MPLS networks and is a local 20-bit opaque value in case of non-MPLS networks.¶
As described in section 4.3 of [RFC9262] and section 5 in [I-D.eckert-bier-rbs], it is necessary to distinguish the BIER and BIER-TE/RBS packet and forwarding. like [RFC8401], [RFC8444], [I-D.ietf-bier-ospfv3-extensions], and [I-D.ietf-bier-lsr-non-mpls-extensions], the MPLS and non-MPLS encapsulation needs to be advertised for BIER-TE/RBS packet encapsulation.¶
The advertisement can follow the existed BIER-TE BP advertisement, but it does not work well if there are many BIER-TE links need to be advertised. Too many octets in the advertisement will be consumed even if the same BIFT-id is used for different links.¶
This document describes the IS-IS and OSPF protocol extensions that are required for BIER-TE/RBS with MPLS and non-MPLS encapsulation associated with prefix distributing.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].¶
This document does not introduce more terminologies than [RFC8279], [RFC8296], [RFC8401], [RFC9262], [I-D.ietf-bier-te-isis], [I-D.ietf-bier-te-ospf], [I-D.ietf-bier-te-ospfv3] and [I-D.eckert-bier-rbs].¶
The BIER-TE MPLS Encapsulation Sub-sub-TLV and BIER-TE non-MPLS Encapsulation Sub-sub-TLV are advertised with BIER-Info Sub-TLV, which is defined in section 6.1 in [RFC8401].¶
As described in section 4.3 in [RFC9262] and section 5 in [I-D.eckert-bier-rbs], the label for MPLS encapsulation or the BIFT-ID for non-MPLS encapsulation is allocatd per SD:BSL.¶
The flooding scope is the same with section 5 in [RFC8401].¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subdomain-id | BS Len| label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BIER-TE MPLS encapsulation Sub-sub-TLV may be advertised many times for different subdomain-id or BS Len.¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subdomain-id | BS Len| BIFT-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BIER-TE non-MPLS encapsulation sub-sub-TLV may be advertised many times for different subdomain-id or BS Len.¶
As described in section 4 of [I-D.ietf-bier-bierin6], which describes how the existing BIER encapsulation specified in [RFC8296] works in a non-MPLS IPv6 network, a node that requires IPv6 encapsulation MUST advertise the BIER-TE IPv6 encapsulation sub-sub-sub-TLV, which follows the associated Non-MPLS Encapsulation, according to local configuration or policy in the BIER domain to request other BFRs to always use IPv6 encapsulation.¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Same with IS-IS, the BIER-TE MPLS Encapsulation Sub-TLV and BIER-TE non-MPLS Encapsulation Sub-TLV are Sub-TLVs of BIER Sub-TLV, which is defined in section 2.1 in [RFC8444].¶
It is similar for OSPFv3, the BIER-TE MPLS Encapsulation Sub-TLV and BIER-TE non-MPLS Encapsulation Sub-TLV are Sub-TLVs of BIER Sub-TLV, which is defined in section 2.1 in [I-D.ietf-bier-ospfv3-extensions].¶
As described in section 4.3 in [RFC9262] and section 5 in [I-D.eckert-bier-rbs], the label for MPLS encapsulation or the BIFT-ID for non-MPLS encapsulation is allocatd per SD:BSL.¶
The format defined below works for both OSPFv2 and OSPFv3. The flooding scope for OSPFv2 is the same with section 2.3 in [RFC8444]. The flooding scope for OSPFv3 is the same with section 2.2 in [I-D.ietf-bier-ospfv3-extensions].¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max SI | Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BS Len| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BIER-TE MPLS encapsulation Sub-TLV may be advertised many times for different subdomain-id or BS Len.¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max SI | BIFT-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BS Len| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BIER-TE non-MPLS encapsulation Sub-TLV may be advertised many times for different subdomain-id or BS Len.¶
As described in section 4 of [I-D.ietf-bier-bierin6], which describes how the existing BIER encapsulation specified in [RFC8296] works in a non-MPLS IPv6 network, a node that requires IPv6 encapsulation MUST advertise the BIER-TE IPv6 encapsulation sub-sub-sub-TLV, which follows the associated Non-MPLS Encapsulation, according to local configuration or policy in the BIER domain to request other BFRs to always use IPv6 encapsulation.¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The document requests new allocations from the IANA registries as follows:¶
BIER-TE MPLS Encapsulation Sub-sub-TLV: TBD (suggested value 3)¶
BIER-TE non-MPLS Encapsulation Sub-sub-TLV: TBD (suggested value 4)¶
IANA is requested to create a registry for "IS-IS BIER-TE non-MPLS Encapsulation Sub-sub-TLV". The type field for the registry consists of 1 octet, with possible values from 1 to 255 (the value 0 is reserved). The allocation policy for this field is to be "First Come First Serve". A "BIER-TE IPv6 encapsulation Sub-sub-sub-TLV" type (TBD, suggested value 1) is requested to be assigned in it.¶
BIER-TE MPLS Encapsulation Sub-TLV: TBD (suggested value 12)¶
BIER-TE non-MPLS Encapsulation Sub-TLV: TBD (suggested value 13)¶
IANA is requested to create a registry for "OSPFv2 BIER-TE non-MPLS Encapsulation Sub-TLV". The type field for the registry consists of 2 octets, with possible values from 1 to 65535 (the value 0 is reserved). The allocation policy for this field is to be "First Come First Serve". A "BIER-TE IPv6 encapsulation Sub-sub-sub-TLV" type (TBD, suggested value 1) is requested to be assigned in it.¶
BIER-TE MPLS Encapsulation Sub-TLV: TBD (suggested value 12)¶
BIER-TE non-MPLS Encapsulation Sub-TLV: TBD (suggested value 13)¶
IANA is requested to create a registry for "OSPFv3 BIER-TE non-MPLS Encapsulation Sub-TLV". The type field for the registry consists of 2 octets, with possible values from 1 to 65535 (the value 0 is reserved). The allocation policy for this field is to be "First Come First Serve". A "BIER-TE IPv6 encapsulation Sub-sub-sub-TLV" type (TBD, suggested value 1) is requested to be assigned in it.¶
This document does not introduce more security considerations than [RFC9262] and [I-D.ietf-bier-te-isis], [I-D.ietf-bier-te-ospf], [I-D.ietf-bier-te-ospfv3] and [I-D.eckert-bier-rbs].¶