# US 11,909,645 B2 · Segment routing traffic engineering based on link utilization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,645 B2 - Document ID: US11909645B2 - Status: Granted - Kind: B2 - Application number: 16/958,991 - Filed: 2019-01-24 - Published: 2020-11-19 - Granted: 2024-02-20 - Earliest claimed: 2018-02-05 - Assignees: Ciena Corporation - Applicants: Ciena Corporation - Inventors: Darek Skalecki; Gerard L. Swinkels - Web page: https://patentgrep.com/patent/US11909645B2 ## CPC - H04L 47/11: Identifying congestion - H04L 43/0882: Utilisation of link capacity - H04L 45/22: {Alternate routing} - H04L 45/34: {Source routing} - H04L 45/50: using label swapping, e.g. multi-protocol label switch [MPLS] - H04L 45/70: {Routing based on monitoring results} - H04L 47/122: by diverting traffic away from congested entities - H04L 47/125: by balancing the load, e.g. traffic engineering - H04L 47/35: by embedding flow control information in regular packets, e.g. piggybacking - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Systems and methods for Segment Routing (SR) Traffic Engineering (SR-TE) in a network include receiving link utilization measurements at a Label Edge Router (LER) with the link utilization measurements flooded by one or more Label Switch Routers (LSRs); and, responsive to one or more of detecting congestion and underutilization on one or more links associated with an SR tunnel at the LER based on the received link utilization measurements, performing one or more actions at the LER to one or more of alleviate the congestion and re-optimize the underutilization. A state of the SR tunnel is maintained only at the LER through a label stack assigned at the LER, and the label stack includes one or more of a node Segment ID (SID) and an adjacency SID. ## Claims ### Claim 1 A Label Edge Router (LER) in a Segment Routing (SR) network configured to perform SR Traffic Engineering (SR-TE), the LER comprising: circuitry configured to: receive link utilization measurements flooded by one or more Label Switch Routers (LSRs) wherein the link utilization measurements are for links associated with one or more SR tunnels; determine whether the one or more SR tunnels are congested, based on one or more of an unreserved bandwidth, a maximum reservable bandwidth, and a maximum bandwidth of corresponding links, where a given SR tunnel is determined to be congested based on one or more of (1) a negative value of the unreserved bandwidth, (2) the maximum reservable bandwidth being greater than the maximum bandwidth, and (3) the maximum reservable bandwidth being equal to the maximum bandwidth; and perform one or more routing actions for the one or more SR tunnels based on the determination. ### Claim 2 (depends on 1) The LER as claimed in claim 1, wherein a state of the one or more SR tunnels is maintained only at the LER through a label stack assigned at the LER, wherein the label stack includes one or more of a node Segment ID (SID) and an adjacency SID. ### Claim 3 (depends on 1) The LER as claimed in claim 1, wherein the link utilization measurements are flooded via existing Interior Gateway Protocol (IGP) Traffic Engineering (TE) extensions. ### Claim 4 (depends on 1) The LER as claimed in claim 1, wherein responsive to the SR tunnel of the one or more SR tunnels being congested the circuitry is further configured to: create a new SR tunnel; and move one or more services off of the SR tunnel that is congested to the new SR tunnel. ### Claim 5 (depends on 1) The LER as claimed in claim 1, wherein the SR tunnel of the one or more SR tunnels is congested, and wherein the circuitry is further configured to: move one or more services off of the congested SR tunnel of the one or more SR tunnels to a next-shortest SR tunnel of the one or more SR tunnels. ### Claim 6 (depends on 1) The LER as claimed in claim 1, wherein the congestion on an associated link of the links associated with the one or more SR tunnels is determined based on the maximum reservable bandwidth. ### Claim 7 A non-transitory computer-readable storage medium having a computer-readable code stored thereon, the computer-readable code that when executed by a processor of a label edge router (LER), causes the LER to perform steps of: receiving link utilization measurements flooded by one or more Label Switch Routers (LSRs) wherein the link utilization measurements are for links associated with one or more SR tunnels; determining whether the one or more SR tunnels are congested, based on one or more of an unreserved bandwidth, a maximum reservable bandwidth, and a maximum bandwidth of corresponding links, where a given SR tunnel is determined to be congested based on one or more of (1) a negative value of the unreserved bandwidth, (2) the maximum reservable bandwidth being greater than the maximum bandwidth, and (3) the maximum reservable bandwidth being equal to the maximum bandwidth; and causing performance of one or more routing actions for the one or more SR tunnels based on the determination. ### Claim 8 (depends on 7) The non-transitory computer-readable storage medium as claimed in claim 7, wherein a state of the one or more SR tunnels is maintained only at the LER through a label stack assigned at the LER, wherein the label stack includes one or more of a node Segment ID (SID) and an adjacency SID. ### Claim 9 (depends on 7) The non-transitory computer-readable storage medium as claimed in claim 7, wherein the link utilization measurements are flooded via existing Interior Gateway Protocol (IGP) Traffic Engineering (TE) extensions. ### Claim 10 (depends on 1) The non-transitory computer-readable storage medium as claimed in claim 1, wherein responsive to the SR tunnel of the one or more SR tunnels being congested the steps further include: causing creation of a new SR tunnel; and causing a move of one or more services off of the SR tunnel that is congested to the new SR tunnel. ### Claim 11 (depends on 7) The non-transitory computer-readable storage medium as claimed in claim 7, wherein the SR tunnel of the one or more SR tunnels is congested, and wherein the steps further include: causing a move of one or more services off of the congested SR tunnel of the one or more SR tunnels to a next-shortest SR tunnel of the one or more SR tunnels. ### Claim 12 (depends on 7) The non-transitory computer-readable storage medium as claimed in claim 7, wherein the congestion on an associated link of the links associated with the one or more SR tunnels is determined based on the maximum reservable bandwidth. ### Claim 13 A method, implemented in a Label Edge Router (LER) in a Segment Routing (SR) network, comprising: receiving link utilization measurements flooded by one or more Label Switch Routers (LSRs) wherein the link utilization measurements are for links associated with one or more SR tunnels; determining whether the one or more SR tunnels are congested, based on one or more of an unreserved bandwidth, a maximum reservable bandwidth, and a maximum bandwidth of corresponding links, where a given SR tunnel is determined to be congested based on one or more of (1) a negative value of the unreserved bandwidth, (2) the maximum reservable bandwidth being greater than the maximum bandwidth, and (3) the maximum reservable bandwidth being equal to the maximum bandwidth; and causing performance of one or more routing actions for the one or more SR tunnels based on the determination. ### Claim 14 (depends on 13) The method as claimed in claim 13, wherein a state of the one or more SR tunnels is maintained only at the LER through a label stack assigned at the LER, wherein the label stack includes one or more of a node Segment ID (SID) and an adjacency SID. ### Claim 15 (depends on 13) The method as claimed in claim 13, wherein the link utilization measurements are flooded via existing Interior Gateway Protocol (IGP) Traffic Engineering (TE) extensions. ### Claim 16 (depends on 13) The method as claimed in claim 13, responsive to the SR tunnel of the one or more SR tunnels being congested, the method further comprising: causing creation of a new SR tunnel; and causing a move of one or more services off of the SR tunnel that is congested to the new SR tunnel. ### Claim 17 (depends on 13) The method as claimed in claim 13, wherein the SR tunnel of the one or more SR tunnels is congested, and the method further comprising: causing a move of one or more services off of the congested SR tunnel of the one or more SR tunnels to a next-shortest SR tunnel of the one or more SR tunnels.