# US 11,909,556 B2 · Resilient multiprotocol label switching (MPLS) rings using segment routing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,556 B2 - Document ID: US11909556B2 - Status: Granted - Kind: B2 - Application number: 17/458,039 - Filed: 2021-08-26 - Published: 2021-12-16 - Granted: 2024-02-20 - Earliest claimed: 2019-07-08 - Assignees: Juniper Networks, Inc. - Applicants: Juniper Networks, Inc. - Inventors: Raveendra Torvi; Abhishek Deshmukh; Kireeti Kompella; Tarek Saad; Vishnu Pavan Beeram; Ronald Bonica - Web page: https://patentgrep.com/patent/US11909556B2 ## CPC - H04L 45/34: {Source routing} - H04L 12/42: Loop networks - H04L 12/437: Ring fault isolation or reconfiguration {(for SDH/SONET ring networks H04J3/085)} - H04L 41/12: Discovery or management of network topologies - H04L 45/02: Topology update or discovery - H04L 45/22: {Alternate routing} - H04L 45/50: using label swapping, e.g. multi-protocol label switch [MPLS] - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A ring node N belonging to a resilient MPLS ring (RMR) provisions and/or configures clockwise (CW) and anti-clockwise (AC) paths on the RMR by: (a) configuring two ring node segment identifiers (Ring-SIDs) on the ring node, wherein a first of the two Ring-SIDs (CW-Ring-SID) is to reach N in a clockwise direction on the ring and a second of the two Ring-SIDs (AC-Ring-SID) is to reach N in an anti-clockwise direction on the ring, and wherein the CW-Ring-SID and AC-Ring-SID are unique within a source packet routing in networking (SPRING) domain including the ring; (b) generating a message including the ring node's CW-Ring-SID and AC-Ring-SID; and (c) advertising the message, via an interior gateway protocol, for receipt by other ring nodes belonging to the ring such that (1) a clockwise multipoint-to-point path (CWP) is defined such that every other one of the ring nodes belonging to the ring can be an ingress for the CWP and such that only the node is an egress for the CWP, and (2) an anti-clockwise multipoint-to-point path (ACP) is defined such that every other one of the ring nodes belonging to the ring can be an ingress for the ACP and such that only the node is an egress for the ACP. ## Claims ### Claim 1 A computer-implemented method for used by a ring node N belonging to a ring, the computer-implemented method comprising: a) receiving, by the ring node N via an interior gateway protocol, a control advertisement message including, for another one of the ring nodes, two ring node segment identifiers (Ring-SIDs), wherein a first of the two Ring-SIDs (CW-Ring-SID) is to reach the other one of the ring nodes in a clockwise direction on the ring and a second of the two Ring-SIDs (AC-Ring-SID) is to reach the other one of the ring nodes in an anti-clockwise direction on the ring, and wherein the CW-Ring-SID and AC-Ring-SID are unique within a source packet routing in networking (SPRING) domain including the ring; b) generating and storing, a first label forwarding information base (LFIB) entry including 1) a node segment identifier (Node-SID) associated with the other one of the ring nodes, or a multiprotocol label switching (MPLS) label derived from the Node-SID, 2) a next hop set to a ring node belonging to the ring and being adjacent and clockwise to the ring node; and c) generating and storing, a second LFIB entry including 1) the Node-SID associated with the other one of the ring nodes, or a multiprotocol label switching (MPLS) label derived from the Node-SID, and 2) a next hop set to a ring node belonging to the ring and being adjacent and anti-clockwise to the ring node, wherein one of the first and second LFIB entries is identified as a primary, and the other of the first and second LFIB entries is identified as a backup. ### Claim 2 (depends on 1) The computer-implemented method of claim 1 wherein the MPLS label is derived from the Node-SID using a minimum or maximum value from a segment routing global block (SRGB) defining a range of label values. ### Claim 3 (depends on 1) The computer-implemented method of claim 1 wherein the control advertisement message including the other one of the ring node's CW-Ring-SID and AC-Ring-SID further includes information for identifying an algorithm used to derive a next hop to reach the other one of the ring nodes. ### Claim 4 (depends on 3) The computer-implemented method of claim 3 wherein the algorithm used to derive a next hop to reach the other one of the ring nodes specifies the use of a specified one of a CW next hop and an AC next hop. ### Claim 5 (depends on 1) The computer-implemented method of claim 1 wherein the control advertisement message received was advertised by flooding it over an interior gateway protocol (IGP) domain. ### Claim 6 (depends on 1) The computer-implemented method of claim 1 wherein the control advertisement message received was advertised within an explicit prefix type-length-value (TLV) interior gateway protocol (IGP) advertisement. ### Claim 7 (depends on 1) The computer-implemented method of claim 1 wherein the control advertisement message received was advertised within a SID/label binding type-length-value (TLV) interior gateway protocol (IGP) advertisement. ### Claim 8 (depends on 1) The computer-implemented method of claim 1 wherein each of the CW-Ring-SID and AC-Ring-SID of the other ring node included in the control advertisement message is expressed as a label value. ### Claim 9 (depends on 1) The computer-implemented method of claim 1 wherein each of the CW-Ring-SID and AC-Ring-SID of the other ring node included in the control advertisement message is expressed as an index defining an offset from one of a start or end of a predefined segment routing global block (SRGB) of labels. ### Claim 10 A node assigned to a ring comprising a subset of n nodes {Ri, 0<=i