BIER IPv6 Encapsulation (BIERv6) Support
via IS-ISHuawei Technologiesxiejingrong@huawei.comChina Telecomwangaj3@chinatelecom.cnHuawei Technologiesyangang@huawei.comHuawei Technologiessenthil.dhanaraj@huawei.comThis document defines IS-IS extensions to support multicast
forwarding using the Bit Index Explicit Replication (BIER) with IPv6
encapsulation (BIERv6).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
and .This document defines IS-IS extensions to support multicast
forwarding using the Bit Index Explicit Replication (BIER) with IPv6
encapsulation (BIERv6).The BIER IPv6 encapsulation uses a "BIER specific" IPv6
unicast address, the "End.BIER" address, configured locally on a BIER
Forwarding Router (BFR) to indicate a "BIER specific handling" in
Forwarding Information Base (FIB). This BIER specific IPv6 address, used
as part of BIER IPv6 encapsulation, is advertised as a type of
Encapsulation sub-sub-TLV within the BIER Info sub-TLV defined
[RFC8401].The BIFT-id field for each BSL of each Sub-domain is another part of
BIER IPv6 encapsulation, and is advertised as a type of Encapsulation
sub-sub-TLV within the BIER Info sub-TLV defined [RFC8401].The BIER Sub-TLV is advertised within the extended IP reachability
TLV as specified by in [RFC8401].Note the extended IP reachability only includes the TLV 236 (IPv6 IP
Reach TLV) [RFC5308] and TLV 237 (MT IPv6 IP Reach TLVs) [RFC5120] in
this document.The following restrictions defined for BIER Sub-TLV in section 4.2 of
[RFC8401] apply equally to this document:Prefix length MUST be 128 for an IPv6 prefix.When the Prefix Attributes Flags sub-TLV [RFC7794] is present,
the N flag MUST be set and the R flag MUST NOT be set.BIER sub-TLVs and Function Sub-TLVs MUST be included when a
prefix reachability advertisement is leaked between levels.Readers of this document are assumed to be familiar with the
terminology and concepts of the documents listed as Normative
References.The Encapsulation sub-sub-TLV carries the information for the
End.BIER address of a sub-domain for BIER IPv6 encapsulation. It is
advertised within the BIER Info sub-TLV defined in [RFC8401] which
in-turn is carried within the TLVs 236 or 237. This sub-sub-TLV MUST
appear no more than one time within a single BIER Info sub-TLV. If the
sub-sub-TLV appears more than one time, the BIER Info sub-TLV MUST be
ignored.Type: 1 octet value indicating "Encapsulation of End.BIER" this
IPv6 prefix bound to. TBD1 to be assigned by IANA.Length: 1 octet length in octets. Value 16 is set to this
field.End.BIER address: 16 octets IPv6 address.The Encapsulation sub-sub-TLV carries the information for the BIER
IPv6 encapsulation of a specific BitString length. It is advertised
within the BIER Info sub-TLV defined in [RFC8401] which in-turn is
carried within the TLVs 236 or 237. This sub-sub-TLV MAY appear
multiple times within a single BIER Info sub-TLV. If the same
BitString length is repeated in multiple sub-sub-TLVs inside the same
BIER Info sub- TLV, the BIER Info sub-TLV MUST be ignored.When a BIER IPv6 encapsulation sub-sub-TLV of BIFT-id for any BSL
appears in a BIER Info sub-TLV, one End.BIER Encapsulation sub-sub-TLV
MUST appears in the BIER info sub-TLV, otherwise the BIER Info sub-TLV
MUST be ignored.Type: 1 octet value indicating BIER IPv6 encapsulation. TBD2 to be
assigned by IANA.Length: 1 octet length in octets. Value 4 is set to this field.Max SI: 1 octet value. Maximum Set Identifier (Section 1 of
[RFC8279]) used in the encapsulation for this BIER subdomain for this
BitString length. Each SI maps to a single BIFT-id in the BIFT-id
range. The first BIFT-id is for SI=0, the second BIFT-id is for SI=1,
etc. If the BIFT-id associated with the Maximum Set Identifier exceeds
the 20-bit range, the sub-sub-TLV MUST be ignored.BS Len: 4 bits value of Local BitString Length. Encoded BitString
length as per [RFC8296].BIFT-id: 20 bits value. First BIFT-id of the range. The BIFT-id(s)
are as defined in [RFC8296], or refer to for Non-MPLS
encapsulation.The procedures of this document do not, in themselves, provide
privacy, integrity, or authentication for the control plane or the data
plane.Allocation is expected from IANA for two sub-sub-TLV codepoints
from the "sub-sub-TLVs for BIER Info sub-TLV" sub-registry.Type: TBD1 to be assigned by IANA.Name: BIER IPv6 encapsulation of End.BIER address.Reference: This document.Type: TBD2 to be assigned by IANA.Name: BIER IPv6 Encapsulation of BIFT-id for each BSL.Reference: This documentTBD.