# US 10,484,333 B2 · Methods and systems for providing limited data connectivity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,484,333 B2 - Document ID: US10484333B2 - Status: Granted - Kind: B2 - Application number: 15/650,913 - Filed: 2017-07-16 - Published: 2019-01-17 - Granted: 2019-11-19 - Earliest claimed: 2017-07-16 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Kabiraj Sethi; Shivangi Sharma; Peter G. Jones; Jimit Maheta - Web page: https://patentgrep.com/patent/US10484333B2 ## CPC - H04L 49/15: Interconnection of switching modules - H04L 45/48: Routing tree calculation - H04L 49/604: {Hybrid IP/Ethernet switches} - H04L 63/0236: {Filtering by address, protocol, port number or service, e.g. IP-address or URL} - 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 41/02: Standardisation; Integration - H04L 43/10: Active monitoring, e.g. heartbeat, ping or trace-route - H04L 69/03: {Protocol definition or specification (protocol conformance testing H04L1/244)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In one embodiment, a system, apparatus, and method are described for providing limited data connectivity for devices connected to a switch when the switch enters bootloader mode. The switch has a central processing unit (CPU), the CPU comprising a reload handler and an application-specific integrated circuit (ASIC), the ASIC comprising ASIC forwarding logic. The ASIC is instructed, by the reload handler, to store an ASIC database, the ASIC database for storing the ASIC forwarding logic. The reload handler maintains a physical layer (PHY) state of the switch. Use of spanning tree protocol (STP) and Transmission Control Protocol (TCP) keepalive is disabled in the switch. A state of stack hardware is retained in switch memory. New ports of the switch are prevented from becoming active, and the ASIC forwarding logic is, in response to receiving the instruction, stored in the ASIC database. Related systems, apparatuses, and methods are also described. ## Claims ### Claim 1 A system comprising: a central processing unit (CPU) comprised in a switch, the CPU comprising a reload handler; and an application-specific integrated circuit (ASIC) in the switch, the ASIC comprising ASIC forwarding logic, upon the switch entering a bootloader mode, the reload handler: maintains a physical layer (PHY) state; instructs the ASIC to store a database comprising the ASIC forwarding logic; disables spanning tree protocol (STP) in the switch; disables use of Transmission Control Protocol (TCP) keepalive in the switch; retains a state of stack hardware in switch memory; and prevents any new ports of the switch from becoming active; and the ASIC storing the ASIC forwarding logic in the database upon receipt of an instruction from the reload handler. ### Claim 2 (depends on 1) The system according to claim 1 wherein at least one device is connected to the switch at a downlink, and upon the switch entering bootloader mode, packets received from the device are forwarded by the switch to an uplink. ### Claim 3 (depends on 2) The system according to claim 2 wherein the at least one device comprises a power over Ethernet (PoE) device. ### Claim 4 (depends on 1) The system according to claim 1 wherein the switch comprises a standalone switch. ### Claim 5 (depends on 4) The system according to claim 4 wherein the reload handler adds a default entry to the ASIC database pointing to a management Ethernet port which is to be used for persistent data. ### Claim 6 (depends on 1) The system according to claim 1 wherein the switch comprises a stackable switch, and the switch is connected to a master switch at a stack interface. ### Claim 7 (depends on 6) The system according to claim 6, wherein, upon a complete stack reload, the reload handler adds an entry in the ASIC database so that a data-path defaults to a management Ethernet port of the management switch for failed look-ups in the ASIC forwarding logic. ### Claim 8 (depends on 1) The system according to claim 1 wherein the switch enters the bootloader mode upon receiving a reload or slot reload command. ### Claim 9 (depends on 1) The system according to claim 1 wherein the switch enters the bootloader mode due to a switch malfunction. ### Claim 10 (depends on 1) The system according to claim 1 wherein the reload handler creates a dynamic destination index upon the switch entering the bootloader mode. ### Claim 11 (depends on 1) The system according to claim 1 wherein the switch is adapted, upon entering the bootloader mode, to not provide power to a new power over Ethernet (PoE) device. ### Claim 12 (depends on 1) The system according to claim 1 wherein the switch, upon performance of a complete stack reload: normally forwards Open Systems Interconnection (OSI) Layer 2 and Layer 3 packets to locations which were previously known; and punts packets which cannot be switched to a next switching level. ### Claim 13 A method comprising: entering a bootloader mode at a switch, the switch comprising; a central processing unit (CPU), the CPU comprising a reload handler; and an application-specific integrated circuit (ASIC), the ASIC comprising ASIC forwarding logic; instructing the ASIC to store an ASIC database, by the reload handler, the ASIC database storing the ASIC forwarding logic; maintaining, by the reload handler, a physical layer (PHY) state; disabling use of spanning tree protocol (STP) in the switch; disabling use of Transmission Control Protocol (TCP) keepalive in the switch; retaining a state of stack hardware in switch memory; preventing any new ports of the switch from becoming active; and storing the ASIC forwarding logic in the ASIC database, by the ASIC. ### Claim 14 (depends on 13) The method according to claim 13 and further comprising, upon the switch entering the bootloader mode, forwarding packets received from at least one device connected to the switch at a downlink, to an uplink. ### Claim 15 (depends on 14) The method according to claim 14 wherein the at least one device comprises a power over Ethernet (PoE) device. ### Claim 16 (depends on 13) The method according to claim 13 wherein the switch comprises a standalone switch. ### Claim 17 (depends on 16) The method according to claim 16 and further comprising the reload handler adding a default entry to the ASIC database pointing to a management Ethernet port which is to be used for persistent data. ### Claim 18 (depends on 13) The method according to claim 13 wherein the switch comprises a stackable switch, and the switch is connected to a master switch at a stack interface. ### Claim 19 (depends on 18) The method according to claim 18 and further comprising the reload handler adding an entry in the ASIC database so that a data-path defaults to a management Ethernet port of a management switch for failed look-ups in the ASIC forwarding logic. ### Claim 20 An apparatus comprising: means for entering a bootloader mode at a switch, the switch comprising; a central processing unit (CPU), the CPU comprising a reload handler; and an application-specific integrated circuit (ASIC), the ASIC comprising ASIC forwarding logic; means for instructing the ASIC to store an ASIC database, the ASIC database storing the ASIC forwarding logic; means for maintaining a physical layer (PHY) state; means for disabling use of spanning tree protocol (STP) in the switch; means for disabling use of Transmission Control Protocol (TCP) keepalive in the switch; means for retaining a state of stack hardware in switch memory; means for preventing any new ports of the switch from becoming active; and means for storing the ASIC forwarding logic in the ASIC database, by the ASIC.