# US 11,451,468 B2 · Management framework for BIER in-band traffic accounting and path monitoring > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,468 B2 - Document ID: US11451468B2 - Status: Granted - Kind: B2 - Application number: 17/160,508 - Filed: 2021-01-28 - Published: 2022-07-28 - Granted: 2022-09-20 - Earliest claimed: 2021-01-28 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Mankamana Prasad Mishra; Rajiv Asati; IJsbrand Wijnands; Stephane Litkowski; Nitin Kumar - Web page: https://patentgrep.com/patent/US11451468B2 ## CPC - H04L 45/16: Multipoint routing - H04L 12/1854: {with non-centralised forwarding system, e.g. chaincast} - H04L 12/4641: {Virtual LANs, VLANs, e.g. virtual private networks [VPN] (LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272)} - H04L 43/026: using flow identification - H04L 43/106: using time related information in packets, e.g. by adding timestamps - H04L 45/24: Multipath - H04L 45/34: {Source routing} - H04L 45/48: Routing tree calculation - H04L 63/0272: {Virtual private networks} - H04L 69/22: Parsing or analysis of headers - H04L 43/0852: Delays - H04L 43/087: Jitter - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method is performed at a router configured to perform Bit Index Explicit Replication (BIER) for forwarding of multicast packets in a network. The method includes, upon receiving a multicast packet of a multicast flow, accessing flow mappings in which multicast flows are mapped to fixed accounting values corresponding to the multicast flows. The method further comprises generating a BIER header for the multicast packet by encoding a multi-segment entropy field of the BIER header with (i) a variable entropy value for equal-cost multi-path (ECMP) load balancing, and (ii) a fixed accounting value among the fixed accounting values that is mapped to the multicast flow in the flow mappings. The method also includes encapsulating the multicast packet with the BIER header to produce an encapsulated multicast packet, and forwarding the encapsulated multicast packet. ## Claims ### Claim 1 A method comprising: at a router configured to perform Bit Index Explicit Replication (BIER) forwarding of multicast packets in a network: upon receiving a multicast packet of a multicast flow, accessing flow mappings in which multicast flows are mapped to fixed accounting values corresponding to the multicast flows; generating a BIER header for the multicast packet by encoding a multi-segment entropy field of the BIER header with (i) a first segment that includes a variable entropy value for equal-cost multi-path (ECMP) load balancing, and (ii) a second segment that includes a fixed accounting value among the fixed accounting values that is mapped to the multicast flow in the flow mappings; encoding a reserved field of the BIER header with an accounting flag configured to indicate that the multi-segment entropy field includes the fixed accounting value, and to trigger next hop BIER routers to perform flow accounting for the multicast flow and reporting accounting results along with the fixed accounting value; encapsulating the multicast packet with the BIER header to produce a BIER packet; and forwarding the BIER packet. ### Claim 2 (depends on 1) The method of claim 1, further comprising, at the router: determining whether the multicast packet belongs to any of the multicast flows in the flow mappings; and when the multicast packet belongs to the multicast flow in the flow mappings, performing the generating. ### Claim 3 (depends on 2) The method of claim 2, wherein: the flow mappings include (source address (S), multicast group address (G)) (S, G) identifiers of the multicast flows that are mapped to the fixed accounting values, and the multicast packet includes an (S, G) identifier of the multicast flow; and the determining includes matching the (S, G) identifier of the multicast packet to the (S, G) identifiers of the flow mappings. ### Claim 4 (depends on 2) The method of claim 2, further comprising, at the router: when the multicast packet does not belong to any of the multicast flows in the flow mappings, not performing the generating and the encapsulating; and encapsulating the multicast packet with a conventional BIER header having an entropy field that only includes a second variable entropy value for the ECMP load balancing. ### Claim 5 (depends on 1) The method of claim 1, wherein the accounting flag is further configured to trigger the next hop BIER routers to perform reporting their identifiers. ### Claim 6 (depends on 1) The method of claim 1, wherein each of the multicast flows is mapped to a distinct fixed accounting value among the fixed accounting values in the flow mappings. ### Claim 7 (depends on 1) The method of claim 1, wherein the multicast flows are divided into distinct sets associated with distinct virtual private networks (VPNs) and each of the distinct sets is mapped to a distinct fixed accounting value among the fixed accounting values of the flow mappings. ### Claim 8 (depends on 1) The method of claim 1, wherein: the generating further includes encoding the reserved field of the BIER header with an egress timestamp corresponding to when the forwarding occurs. ### Claim 9 (depends on 8) The method of claim 8, wherein: the generating further includes encoding the reserved field with a timing flag to indicate that the reserved field includes the egress timestamp. ### Claim 10 (depends on 1) The method of claim 1, wherein the fixed accounting values include one or more virtual private network (VPN) identifiers. ### Claim 11 (depends on 1) The method of claim 1, wherein the router is an ingress router of the network. ### Claim 12 (depends on 1) The method of claim 1, further comprising, at a second router in the network: receiving the BIER packet forwarded by the router; parsing the BIER header to retrieve the fixed accounting value; and sending, to a controller of the network, a message including an identifier of the second router and the fixed accounting value. ### Claim 13 An apparatus comprising: multiple network input/output interfaces; and a processor of a router configured to perform Bit Index Explicit Replication (BIER) forwarding of multicast packets in a network, the processor coupled to the multiple network input/output interfaces and configured to perform: upon receiving a multicast packet of a multicast flow, accessing flow mappings in which multicast flows are mapped to fixed accounting values corresponding to the multicast flows; generating a BIER header for the multicast packet by encoding a multi-segment entropy field of the BIER header with (i) a first segment that includes a variable entropy value for equal-cost multi-path (ECMP) load balancing, and (ii) a second segment that includes a fixed accounting value among the fixed accounting values that is mapped to the multicast flow in the flow mappings; encoding a reserved field of the BIER header with an accounting flag configured to indicate that the multi-segment entropy field includes the fixed accounting value, and to trigger next hop BIER routers to perform flow accounting for the multicast flow and reporting accounting results along with the fixed accounting value; encapsulating the multicast packet with the BIER header to produce a BIER packet; and forwarding the BIER packet. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the processor is further configured to perform: determining whether the multicast packet belongs to any of the multicast flows in the flow mappings; and when the multicast packet belongs to the multicast flow in the flow mappings, performing the generating. ### Claim 15 (depends on 13) The apparatus of claim 13, wherein the accounting flag is further configured to trigger the next hop BIER routers to perform reporting their identifiers. ### Claim 16 (depends on 13) The apparatus of claim 13, wherein: the generating further includes encoding the reserved field of the BIER header with an egress timestamp corresponding to when the forwarding occurs. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein: the generating further includes encoding the reserved field with a timing flag to indicate that the reserved field includes the egress timestamp. ### Claim 18 A non-transitory computer readable medium encoded with instructions that, when executed by a processor of a router configured to perform Bit Index Explicit Replication (BIER) forwarding of multicast packets in a network, cause the processor to perform: upon receiving a multicast packet of a multicast flow, accessing flow mappings in which multicast flows are mapped to fixed accounting values corresponding to the multicast flows; generating a BIER header for the multicast packet by encoding a multi-segment entropy field of the BIER header with (i) a first segment that includes a variable entropy value for equal-cost multi-path (ECMP) load balancing, and (ii) a second segment that includes a fixed accounting value among the fixed accounting values that is mapped to the multicast flow in the flow mappings; encoding a reserved field of the BIER header with an accounting flag configured to indicate that the multi-segment entropy field includes the fixed accounting value, and to trigger next hop BIER routers to perform flow accounting for the multicast flow and reporting accounting results along with the fixed accounting value; encapsulating the multicast packet with the BIER header to produce a BIER packet; and forwarding the BIER packet. ### Claim 19 (depends on 18) The non-transitory computer readable medium of claim 18, wherein the accounting flag is further configured to trigger the next hop BIER routers to perform reporting their identifiers. ### Claim 20 (depends on 18) The non-transitory computer readable medium of claim 18, wherein the instructions to cause the processor to perform the generating include instructions to cause the processor to perform encoding the reserved field of the BIER header with an egress timestamp corresponding to when the forwarding occurs.