US Patent 11582148 MPLS extension headers for in-network services

Described herein are methods and devices (e.g., routers) that add in-network services to a multiprotocol label switching (MPLS) network. A method can include a router of the MPLS network receiving a packet and modifying the packet by adding one or more MPLS extension headers, adding a header of the extension header(s), and adding an indication within an MPLS label stack that one or more MPLS extension headers have been added to the packet. The method can also include the router forwarding the packet as modified to another router of the MPLS network. In certain embodiments, an extension header label (EHL) within a label value field of a label stack entry indicates that one or more MPLS extension headers have been added to the packet. In other embodiments, a forward equivalent class (FEC) indicates that one or more MPLS extension headers follow the MPLS label stack.