Segment routing policies with an IPv6 data plane

Segment routing policies with an IPv6 data plane (SRv6 policies) can be used as a part of traffic engineering in SRv6. SRv6 policies build on the concepts introduced with SR policies with an MPLS data plane :

• The SRv6 policies use SRv6 SIDs instead of MPLS labels as SIDs in the segment list and as binding SID. The SIDs can be encapsulated in a segment routing header (SRH).
• SRv6 polices can be statically configured on the router or programmed through BGP.

The router supports uncompressed 128-bit SRv6 SIDs as the binding SID and as SIDs for the segments in the segment lists. The binding SID and all segment list SIDs must be of the same type, that is, MPLS labels or SRv6 SIDs. The SRv6 SID can correspond to a 128-bit SID of any function type (for example, node SID, adjacency SID, binding SID).

At the head end of an SRv6 policy, service packets are encapsulated in the SRv6 packet using a head end behavior type. The following table lists the head end behavior types specified in RFC 8986.

H.Encaps	SR head end with encapsulation in an SR policy
H.Encaps.Red	H.Encaps with reduced encapsulation
H.Encaps.L2	H.Encaps applied to received L2 frames
H.Encaps.L2.Red	H.Encaps.Red applied to received L2 frames

SR OS supports the following head end behavior types:

• H.Encaps.Red
• H.Encaps.L2.Red

The supported types are an optimization of the corresponding H.Encaps behavior types, that is, they exclude the first SID in the SRH of the pushed IPv6 header to reduce the length of the SRH. The Destination Address field of the pushed IPv6 header contains the first SID, while the SRH contains the other SIDs and the service SID.