IPv6 Hop-by-Hop Options Extension Header
The IPv6 Hop-by-Hop Options extension header is a component of the IPv6 protocol suite that allows for the insertion of optional information that must be examined by every node along a packet's delivery path. Introduced in IPv6 to replace the IPv4 options field, this extension header is identified by the next header field in the IPv6 fixed header. It can include various options such as routing information, quality of service (QoS) parameters, and timestamping. When present, the Hop-by-Hop Options extension header must be examined and processed by every intermediate router or host that handles the packet. This header provides flexibility and extensibility to the IPv6 protocol, allowing for the addition of new options without modifying the IPv6 base header. However, its use is relatively rare, as most optional information can be efficiently handled using other IPv6 extension headers. s://datatracker.ietf.org/doc/html/rfc2460#section-4.3