IPv6 Segment Routing (SR) is an SDN technology supporting IPv6 forwarding. In SR, a source or edge router performs source
routing of traffic and encodes it as a segment list in an IPv6 routing extension header. The network is not required to maintain
a per-application or per-flow state.
Any IPv6 capable node in a network may forward IPv6 traffic with an SR extension header to the first segment in the segment
list without supporting IPv6 Segment Routing (SRv6).
At the node that hosts the current segment in the segment list, SRv6 is configured to modify the destination address of the
traffic containing the SR extension header and destined to that segment ID. As part of SRv6 final processing, the next segment
ID in the SR extension header is written to the destination address of the packet and a lookup is performed to forward the
traffic to the new destination address.
The forwarding and SRv6 end processing continues at nodes hosting the segment IDs in the SR extension header until the last
segment in the list is removed and the traffic is delivered to its ultimate destination.