# US 10,374,936 B2 · Reducing false alarms when using network keep-alive messages > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,936 B2 - Document ID: US10374936B2 - Status: Granted - Kind: B2 - Application number: 14/984,926 - Filed: 2015-12-30 - Published: 2017-07-06 - Granted: 2019-08-06 - Earliest claimed: 2015-12-30 - Assignees: Juniper Networks, Inc. - Applicants: Juniper Networks, Inc. - Inventors: Prashant Singh; Sairam Neelam - Web page: https://patentgrep.com/patent/US10374936B2 ## CPC - H04L 45/026: {Details of "hello" or keep-alive messages} - H04L 41/5003: Managing SLA; Interaction between SLA and QoS - H04L 43/10: Active monitoring, e.g. heartbeat, ping or trace-route - H04L 67/145: avoiding end of session, e.g. keep-alive, heartbeats, resumption message or wake-up for inactive or interrupted session - H04L 67/61: taking into account QoS or priority requirements - H04L 69/28: Timers or timing mechanisms used in protocols - H04L 45/28: using route fault recovery - H04L 47/2466: using signalling traffic - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Techniques are described to reduce false alarms in network devices utilizing keepalive messaging schemes. In order to potentially avoid false alarms, a transmitting network device adjusts quality of service QOS/TOS settings in keep-alive probe packets that are sent later in a current detection interval such that the keep-alive probe packets have escalating priorities. In addition, for keep-alive probe packets that are sent later in the current detection interval, the network device may also insert host-level preferential indicator within each of the packets to request preferential treatment at both itself and the peer network device. ## Claims ### Claim 1 A method comprising: maintaining, with a network device, a keep-alive transmit timer and a keep-alive detection timer associated with a communication session with a peer network device within a network, wherein the keep-alive transmit timer defines a transmit time interval for transmitting keep-alive probe packets for the communication session and the keep-alive detection timer defines a current detection interval within which a response communication from the peer network device must be received to avoid a failure event for the communication session; responsive to expiration of the keep-alive transit timer during the current detection interval, outputting, by the network device, a first keep-alive probe packet associated with the communication session with the peer network device, wherein the first keep-alive probe packet includes quality of service (QoS) settings that control forwarding priority of the keep-alive probe packet by packet-switching devices within the network, and wherein the QoS settings have a value indicating a first priority level; and responsive to a second expiration of the keep-alive transit timer associated with the current detection interval, determining, by the network device, whether a communication has been received from the peer network device since output of the first keep-alive probe packet and, when the communication has not been received, outputting a second keep-alive probe packet associated with the communication session, wherein the second keep-alive probe packet includes QoS settings having a value indicating a second priority level increased from the first priority level. ### Claim 2 (depends on 1) The method of claim 1, wherein the first keep-alive probe packet and the second keep-alive probe packet each includes a host-level preferential indicator separate from the QoS settings that specifies preferential treatment for the first keep-alive probe packet by packet processing software or hardware on the network device when outputting the first keep-alive probe packet and by packet processing software or hardware on the peer network device when receiving the first keep-alive probe packet, wherein the network device sets the host-level preferential indicator of the first keep-alive probe packet to have a first value indicating that preferential treatment is not requested, and wherein, when the communication from the peer network device has not been received, the network device sets the host-level preferential indicator of the second keep-alive probe packet to have a second value indicating that preferential treatment is requested. ### Claim 3 (depends on 2) The method of claim 2, wherein the host-level preferential indicator comprise one of: a flag set within a reserved Transmission Control Protocol (TCP) bit, a flag set within an unused bidirectional forwarding detection (BFD) protocol diagnostic bit, or an unused Internet Protocol (IP) options bit. ### Claim 4 (depends on 1) The method of claim 1, wherein the communication from the peer network device comprises a keep-alive response packet sent by the peer network device to the network device on the communication session. ### Claim 5 (depends on 1) The method of claim 1, wherein the communication from the peer network device comprises a keep-alive probe packet sent by the peer network device to the network device on a second communication session. ### Claim 6 (depends on 1) The method of claim 1, wherein the communication session comprises a bidirectional forwarding detection (BFD) protocol session between the network device and the peer network device, wherein the first keep-alive probe packet and the second keep-alive probe packets output by the network device comprises BFD keep-alive probe packets, and wherein the communication from the peer network device comprises a BFD keep-alive probe packet sent by the peer network device to the network device on a second communication session. ### Claim 7 (depends on 1) The method of claim 1, further comprising: receiving, by the peer network device, the first keep-alive probe packet; constructing, with the peer network device, a keep-alive response packet, wherein constructing the keep-alive response packet includes copying the QoS settings of the first keep-alive probe packet to QoS settings within the keep-alive response packet; and outputting the keep-alive response packet from the peer device to the network device. ### Claim 8 (depends on 7) The method of claim of claim 7, wherein the first keep-alive probe packet includes a host-level preferential indicator that specifies preferential treatment for the first keep-alive probe packet by packet processing software or hardware on the network device when outputting the first keep-alive probe packet and by packet processing software or hardware on the peer network device when receiving the first keep-alive probe packet, and wherein constructing the keep-alive response packet with the peer network device includes copying the host-level preferential indicator of the first keep-alive probe packet received from the network device to a host-level preferential indicator within the keep-alive response packet. ### Claim 9 A method comprising: receiving, by a network device, a keep-alive probe packet associated with a communication session with a peer network device within a network, wherein the keep-alive probe packet includes quality of service (QoS) settings that controls forwarding priority of the keep-alive probe packet by packet-switching devices within the network; constructing, with the network device, a keep-alive response packet, wherein constructing the keep-alive response packet includes copying the QoS settings of the keep-alive probe packet to QoS settings within the keep-alive response packet; and outputting the keep-alive response packet from the network device to the peer network device; wherein the keep-alive probe packet includes a host-level preferential indicator that specifies preferential treatment for the keep-alive probe packet by packet processing software or hardware on the network device when receiving the keep-alive probe packet and by packet processing software or hardware on the peer network device when transmitting the keep-alive probe packet, and wherein constructing the keep-alive response packet with the network device includes copying the host-level preferential indicator of the keep-alive probe packet received from the network device to a host-level preferential indicator within the keep-alive response packet. ### Claim 10 A network device comprising: one or more programmable processors coupled to a memory storing instructions and at least one network interface; and wherein, when executing the instructions, the processor is configured to: maintain a keep-alive transmit timer and a keep-alive detection timer associated with a communication session with a peer network device within a network, wherein keep-alive transmit timer defines a transmit time interval for transmitting keep-alive probe packets for the communication session and the keep-alive detection timer defines a current detection interval within which a response communication from the peer network device must be received to avoid a failure event for the communication session; responsive to expiration of the keep-alive transit timer during the current detection interval, output a first keep-alive probe packet associated with the communication session with the peer network device, wherein the first keep-alive probe packet includes quality of service (QoS) settings that control forwarding priority of the keep-alive probe packet by packet-switching devices within the network, and wherein the QoS settings have a value indicating a first priority level; responsive to a second expiration of the keep-alive transit timer associated with the current detection interval, determine whether a communication has been received from the peer network device since output of the first keep-alive probe packet and, when the communication has not been received, output a second keep-alive probe packet associated with the communication session, wherein the second keep-alive probe packet includes QoS settings having a value indicating a second priority level increased from the first priority level. ### Claim 11 (depends on 10) The network device of claim 10, wherein the first keep-alive probe packet and the second keep-alive probe packet each includes a host-level preferential indicator separate from the QoS settings that specifies preferential treatment for the first keep-alive probe packet by packet processing software or hardware on the network device when outputting the first keep-alive probe packet and by packet processing software or hardware on the peer network device when receiving the first keep-alive probe packet, wherein the network device sets the host-level preferential indicator of the first keep-alive probe packet to have a first value indicating that preferential treatment is not requested, and wherein, when the communication from the peer network device has not been received, the network device sets the host-level preferential indicator of the second keep-alive probe packet to have a second value indicating that preferential treatment is requested. ### Claim 12 (depends on 11) The network device of claim 11, wherein the host-level preferential indicator comprise one of: a flag set within a reserved Transmission Control Protocol (TCP) bit, a flag set within an unused bidirectional forwarding detection (BFD) protocol diagnostic bit, or an unused Internet Protocol (IP) options bit. ### Claim 13 (depends on 10) The network device of claim 10, wherein the communication from the peer network device comprises a keep-alive response packet sent by the peer network device to the network device on the communication session. ### Claim 14 (depends on 10) The network device of claim 10, wherein the communication from the peer network device comprises a keep-alive probe packet sent by the peer network device to the network device on a second communication session. ### Claim 15 (depends on 10) The network device of claim 10, wherein the communication session comprises a bidirectional forwarding detection (BFD) protocol session between the network device and the peer network device, wherein the first keep-alive probe packet and the second keep-alive probe packets output by the network device comprises BFD keep-alive probe packets, and wherein the communication from the peer network device comprises a BFD keep-alive probe packet sent by the peer network device to the network device on a second communication session. ### Claim 16 A network device comprising: one or more programmable processors coupled to a memory storing instructions and at least one network interface; and wherein, when executing the instructions, the processor is configured to: receive, by a network device, a keep-alive probe packet associated with a communication session with a peer network device within a network, wherein the keep-alive probe packet includes quality of service (QoS) settings that controls forwarding priority of the keep-alive probe packet by packet-switching devices within the network; construct, with the network device, a keep-alive response packet, wherein constructing the keep-alive response packet includes copying the QoS settings of the keep-alive probe packet to QoS settings within the keep-alive response packet; and output the keep-alive response packet from the network device to the peer network device; wherein the keep-alive probe packet includes a host-level preferential indicator that specifies preferential treatment for the keep-alive probe packet by packet processing software or hardware on the network device when receiving the keep-alive probe packet and by packet processing software or hardware on the peer network device when transmitting the keep-alive probe packet, and wherein constructing the keep-alive response packet with the network device includes copying the host-level preferential indicator of the keep-alive probe packet received from the network device to a host-level preferential indicator within the keep-alive response packet.