Multicast based on penultimate hop popping

Abstract

Various example embodiments for supporting multicast are presented. Various example embodiments for supporting multicast are configured to support multicast, on a multicast tree for a multicast group, based on use of penultimate hop popping (PHP) on the multicast tree. Various example embodiments for supporting multicast are configured to support multicast, on a multicast tree for a multicast group, based on use of PHP on the multicast tree where the multicast tree is Point-to-Multipoint (P2MP) Multiprotocol Label Switching (MPLS) tree that is formed based on a TREE-SID multicast solution (although it will be appreciated that PHP may be applied on other types of multicast trees (e.g., other than P2MP MPLS multicast trees), on multicast trees formed based on other multicast solutions (e.g., other than TREE-SID), or the like, as well as various combinations thereof).

1 - 22 . (canceled) 
     
     
         23 . An apparatus, comprising:
 at least one processor; and   at least one memory including program code;   wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 determine a multicast tree for a multicast group, wherein the multicast tree includes a root router, a set of transit routers, and a set of leaf routers; and 
 establish the multicast tree based on an indication that penultimate hop popping (PHP) is to be used on the multicast tree. 
   
     
     
         24 . The apparatus of  claim 23 , wherein, to determine the multicast tree, the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 receive network topology information from the communication network;   receive multicast tree root and leaf information identifying the root router and the set of leaf routers; and   calculate the multicast tree from the root router to the set of leaf routers based on the network topology information and the multicast tree root and leaf information.   
     
     
         25 . The apparatus of  claim 24 , wherein the multicast tree root and leaf information is received from the root router. 
     
     
         26 . The apparatus of  claim 23 , wherein, to establish the multicast tree based on an indication that PHP is to be used on the multicast tree, the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 determine multicast tree configuration information for the root router and the transit routers; and   send the multicast tree configuration information toward the root router and the transit routers.   
     
     
         27 . The apparatus of  claim 23 , wherein, to establish the multicast tree based on an indication that PHP is to be used on the multicast tree, the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 identify, from the set of transit routers, one or more penultimate hop (PH) routers of the multicast tree; and   send, toward each of the one or more PH routers of the multicast tree, respective multicast tree configuration information indicative that the respective PH router is to remove a tree label of the multicast tree from multicast packets on the multicast tree before forwarding the multicast packets via the multicast tree.   
     
     
         28 . The apparatus of  claim 27 , wherein, for at least one of the PH routers of the multicast tree, the multicast tree configuration information includes a rule indicative that the tree label of the multicast tree is to be swapped with an implicit null label. 
     
     
         29 . An apparatus, comprising:
 at least one processor; and   at least one memory including program code;   wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 determine, by a root router of a multicast tree, that penultimate hop popping (PHP) is to be used on the multicast tree; and 
 send, by the root router toward a controller, an indication that PHP is to be used on the multicast tree. 
   
     
     
         30 . The apparatus of  claim 29 , wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 determine, by the root router of the multicast tree, that it is to operate as the root router of the multicast tree; and   send, by the root router toward the controller, an indication that it is to operate as the root router of the multicast tree.   
     
     
         31 . The apparatus of  claim 29 , wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 discover, by the root router, one or more leaf routers of the multicast tree; and   send, by the root router toward the controller, an indication of the one or more leaf routers of the multicast tree.   
     
     
         32 . The apparatus of  claim 31 , wherein the one or more leaf routers of the multicast tree are discovered based on use of Multi-protocol BGP (MP-BGP) in conjunction with Multicast Virtual Private Network (MVPN) procedures. 
     
     
         33 . The apparatus of  claim 31 , wherein the one or more leaf routers of the multicast tree are discovered based on MP-BGP LEAF auto-discovery (AD) routes arriving at the root router from the one or more leaf routers. 
     
     
         34 . The apparatus of  claim 29 , wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 advertise, by the root router to one or more leaf routers, a label identifying a virtual routing and forwarding (VRF) instance of the multicast tree.   
     
     
         35 . An apparatus, comprising:
 at least one processor; and   at least one memory including program code;   wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 receive, by a penultimate hop (PH) router of a multicast tree, a multicast packet including a tree label identifying the multicast tree, an upstream assigned label, and a multicast payload; 
 remove, by the PH router, the tree label from the multicast packet to form a modified multicast packet; and 
 send, by the PH router toward one or more leaf routers of the multicast tree via the multicast tree, the modified multicast packet. 
   
     
     
         36 . The apparatus of  claim 35 , wherein the tree label is removed from the multicast packet by popping the tree label from the multicast packet. 
     
     
         37 . The apparatus of  claim 36 , wherein the tree label is popped from the multicast packet based on a rule indicative that the tree label is to be swapped with an implicit null label. 
     
     
         38 . The apparatus of  claim 37 , wherein the rule indicative that the tree label is to be swapped with the implicit null label is received from a controller. 
     
     
         39 . The apparatus of  claim 35 , wherein the upstream assigned label maps to a virtual routing and forwarding (VRF) instance of the multicast tree. 
     
     
         40 . An apparatus, comprising:
 at least one processor; and   at least one memory including program code;   wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 receive, by a leaf router of a multicast tree from a penultimate hop router of the multicast tree, a multicast packet including a multicast payload and having an upstream assigned label as an outer label; and 
 determine, by the leaf router based on the upstream assigned label and the multicast payload, forwarding of the multicast payload from the leaf router. 
   
     
     
         41 . The apparatus of  claim 40 , wherein the multicast packet is received without a tree label identifying the multicast tree. 
     
     
         42 . The apparatus of  claim 40 , wherein, to determine forwarding of the multicast payload from the leaf router, the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus to at least:
 identify, based on the upstream assigned label, a virtual routing and forwarding (VRF) instance of the multicast tree; and   identify, based on the VFR instance for the multicast tree and a header of the multicast payload, one or more outgoing interfaces of the leaf router via which the multicast payload is to be forwarded.   
     
     
         43 . The apparatus of  claim 42 , wherein the one or more outgoing interface of the leaf router are identified based on an Internet Protocol (IP) header of the multicast payload. 
     
     
         44 . The apparatus of  claim 42 , wherein a mapping of the upstream assigned label to the VRF instance of the multicast tree is received from a root router of the multicast tree.