# US 2019/0245708 A1 · Fast recovery of multicast router ports on spanning tree protocol (stp) topology change in a layer 2 (l2) network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0245708 A1 - Document ID: US20190245708A1 - Status: Published application - Kind: A1 - Application number: 16/384,623 - Filed: 2019-04-15 - Published: 2019-08-08 - Earliest claimed: 2015-01-15 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Chidambaram Bhagavathiperumal; Angu Selvam Chandra Sekaran; Suryanarayan Ramamurthy; Jun Yao; Yuan Yuan Zhang - Web page: https://patentgrep.com/patent/US20190245708A1 ## CPC - H04L 45/28: using route fault recovery - H04L 12/185: {with management of multicast group membership} - H04L 12/1863: {comprising mechanisms for improved reliability, e.g. status reports (arrangements for detecting or preventing errors by carrying supervisory signal the return channel H04L1/16)} - H04L 12/1868: {Measures taken after transmission, e.g. acknowledgments} - H04L 41/0661: {by reconfiguring faulty entities} - H04L 41/0816: the condition being an adaptation, e.g. in response to network events - H04L 43/0811: by checking connectivity - H04L 45/16: Multipoint routing - H04L 45/48: Routing tree calculation - H04L 49/65: Re-configuration of fast packet switches - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In one embodiment, an apparatus includes a processing circuit and logic integrated with and/or executable by the processing circuit. The logic is configured to cause the processing circuit to handle Internet Group Membership Protocol (IGMP) messages received from other devices in a network. Also, the logic is configured to cause the processing circuit to create a general query solicit (GQS) message configured to solicit a general query (GQ) from a multicast snooping querier coupled with the apparatus. The GQS message causes the multicast snooping querier to send out a general query (GQ) message on all ports in response to receiving the GQS message. The GQ message is configured to solicit port information and group membership information from each IGMP switch in the network. Other systems, methods, and computer program products are described in more embodiments. ## Claims ### Claim 1 An apparatus, comprising: a processing circuit; logic integrated with and/or executable by the processing circuit, the logic being configured to cause the processing circuit to: handle Internet Group Membership Protocol (IGMP) messages received from other devices in a network; and create a general query solicit (GQS) message configured to solicit a general query (GQ) from a multicast snooping querier coupled with the apparatus, wherein the GQS message causes the multicast snooping querier to send out a general query (GQ) message on all ports in response to receiving the GQS message, wherein the GQ message is configured to solicit port information and group membership information from each IGMP switch in the network. ### Claim 2 (depends on 1) The apparatus as recited in claim 1, wherein the multicast snooping querier is a multicast router, an IGMP router, or an IGMP switch. ### Claim 3 (depends on 1) The apparatus as recited in claim 1, wherein the logic further causes the processing circuit to: determine that a link coupled to another IGMP switch in the network has failed prior to creating the GQS message; and send the GQS message out on all forwarding ports except for a port coupled to the failed link. ### Claim 4 (depends on 3) The apparatus as recited in claim 3, wherein the logic further causes the processing circuit to respond to: receive a second GQ message; and respond to the second GQ message with a response that includes port information and group membership information to enable the multicast snooping querier to build a multicast routing tree. ### Claim 5 (depends on 1) The apparatus as recited in claim 1, wherein the GQS message has a type field set to 0xF1. ### Claim 6 A method, comprising: handling, using a switch in a network, Internet Group Membership Protocol (IGMP) messages received from other devices in the network; and creating, using the switch, a general query solicit (GQS) message configured to solicit a general query (GQ) from a multicast snooping querier coupled with the switch, wherein the GQS message causes the multicast snooping querier to send out a general query (GQ) message on all ports in response to receiving the GQS message, the GQ message being configured to solicit port information and group membership information from each IGMP switch in the network. ### Claim 7 (depends on 6) The method as recited in claim 6, wherein the multicast snooping querier is a multicast router, an IGMP router, or an IGMP switch. ### Claim 8 (depends on 6) The method as recited in claim 6, comprising: determining that a link coupled to another IGMP switch in the network has failed prior to creating the GQS message; and sending the GQS message out on all forwarding ports except for a port coupled to the failed link. ### Claim 9 (depends on 6) The method as recited in claim 6, comprising: receiving a second GQ message; and responding to the second GQ message with a response that includes port information and group membership information to enable the multicast snooping querier to build a multicast routing tree. ### Claim 10 (depends on 6) The method as recited in claim 6, wherein the GQS message has a type field set to 0xF1. ### Claim 11 A computer program product, comprising a computer readable storage medium having program instructions embodied therewith, the program instructions being executable by a processor of a switch to cause the processor to: handle, by the processor, Internet Group Membership Protocol (IGMP) messages received from other devices in a network; create, by the processor, a general query solicit (GQS) message configured to solicit a general query (GQ) from a multicast snooping querier coupled with the switch; receive, by the processor, a GQ message; and respond, by the processor, to the GQ message with a response that includes port information and group membership information to enable the multicast snooping querier to build a multicast routing tree. ### Claim 12 (depends on 11) The computer program product as recited in claim 11, wherein the multicast snooping querier is a multicast router, an IGMP router, or an IGMP switch. ### Claim 13 (depends on 11) The computer program product as recited in claim 11, wherein the GQS message causes the multicast snooping querier to send out a second GQ message on all ports in response to receiving the GQS message. ### Claim 14 (depends on 13) The computer program product as recited in claim 13, wherein the second GQ message is configured to solicit port information and group membership information from each IGMP switch in the network. ### Claim 15 (depends on 11) The computer program product as recited in claim 11, wherein the program instructions are further executable to cause the processor to: determine, by the processor, that a link coupled to another IGMP switch in the network has failed prior to creating the GQS message; and send, by the processor, the GQS message out on all forwarding ports except for a port coupled to the failed link. ### Claim 16 (depends on 11) The computer program product as recited in claim 11, wherein the GQS message has a type field set to 0xF1. ### Claim 17 (depends on 11) An apparatus, comprising: a processor; and the computer program product as recited in claim 11.