# US 2022/0286401 A1 · Priority-based flow control messaging for port extender > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0286401 A1 - Document ID: US20220286401A1 - Status: Published application - Kind: A1 - Application number: 17/825,316 - Filed: 2022-05-26 - Published: 2022-09-08 - Earliest claimed: 2019-12-10 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Aviran Kadosh - Web page: https://patentgrep.com/patent/US20220286401A1 ## CPC - H04L 47/2483: involving identification of individual flows - H04L 41/0803: Configuration setting - H04L 41/0806: for initial configuration or provisioning, e.g. plug-and-play - H04L 43/026: using flow identification - H04L 43/0876: Network utilisation, e.g. volume of load or congestion level - H04L 47/12: Avoiding congestion; Recovering from congestion - H04L 47/31: by tagging of packets, e.g. using discard eligibility [DE] bits - H04L 49/25: Routing or path finding in a switch fabric - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A port extender provides individual flow control for ports multiplexed from a network device. The port extender is configured to multiplex a network device port across the front panel ports on the port extender. The port extender also determines that an input buffer for the network device port is overloaded, and generates a Priority-based Flow Control (PFC) frame identifying that the network device port is congested. The port extender sends the PFC frame via the network device port to the network device. The PFC frame causes the network device coupled to the network device port to discontinue sending data for transmission from the plurality of ports on the port extender. ## Claims ### Claim 1 A method comprising: configuring a port extender to multiplex a network device port across a plurality of ports on the port extender; determining that an input buffer for the network device port is overloaded; generating a priority-based flow control (PFC) frame identifying that the network device port is congested; and sending the PFC frame via the network device port, wherein the PFC frame causes a network device coupled to the network device port to discontinue sending data for transmission from the plurality of ports on the port extender. ### Claim 2 (depends on 1) The method of claim 1, wherein the PFC frame identifies that the network device port is congested through a priority vector of the PFC frame. ### Claim 3 (depends on 2) The method of claim 2, wherein the PFC frame identifies that the network device port is congested by using a predetermined value for the priority vector of the PFC frame. ### Claim 4 (depends on 1) The method of claim 1, wherein the port extender is configured to multiplex the network device port across the plurality of ports on the port extender based on a special tag. ### Claim 5 (depends on 1) The method of claim 1, wherein determining that the input buffer for the network device port is overloaded is based on an amount of data in the input buffer. ### Claim 6 (depends on 1) The method of claim 1, wherein determining that the input buffer for the network device port is overloaded is based on a rate of information filling the input buffer. ### Claim 7 (depends on 1) The method of claim 1, wherein the PFC frame causes the network device to halt data transmissions for a plurality of output queues associated with the plurality of ports on the port extender. ### Claim 8 An apparatus comprising: a network device port configured to communicate with a network device; a plurality of ports configured to transmit and receive data from one or more networks; and a processor configured to: multiplex the network device port across the plurality of ports; determine that an input buffer for the network device port is overloaded; generate a priority-based flow control (PFC) frame identifying that the network device port is congested; and send the PFC frame via the network device port, wherein the PFC frame causes a network device coupled to the network device port to discontinue sending data for transmission from the plurality of ports. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein the PFC frame identifies that the network device port is congested through a priority vector of the PFC frame. ### Claim 10 (depends on 9) The apparatus of claim 9, wherein the PFC frame identifies that the network device port is congested by using a predetermined value for the priority vector of the PFC frame. ### Claim 11 (depends on 8) The apparatus of claim 8, wherein the processor is configured to multiplex the network device port across the plurality of ports on the port extender based on a special tag. ### Claim 12 (depends on 8) The apparatus of claim 8, wherein the processor is configured to determine that the input buffer for the network device port is overloaded based on an amount of data in the input buffer. ### Claim 13 (depends on 8) The apparatus of claim 8, wherein the processor is configured to determine that the input buffer for the network device port is overloaded is based on a rate of information filling the input buffer. ### Claim 14 (depends on 8) The apparatus of claim 8, wherein the PFC frame sent by the processor causes the network device to halt data transmissions for a plurality of output queues associated with the plurality of ports on the port extender. ### Claim 15 One or more non-transitory computer readable storage media encoded with software comprising computer executable instructions and when the software is executed operable to cause a processor to: configure a port extender to multiplex a network device port across a plurality of ports on the port extender; determine that an input buffer for the network device port is overloaded; generate a priority-based flow control (PFC) frame identifying that the network device port is congested; and send the PFC frame via the network device port, wherein the PFC frame causes the network device coupled to the network device port to discontinue sending data for transmission from the plurality of ports on the port extender. ### Claim 16 (depends on 15) The one or more non-transitory computer readable storage media of claim 15, wherein the PFC frame identifies that the network device port is congested through a priority vector of the PFC frame. ### Claim 17 (depends on 16) The one or more non-transitory computer readable storage media of claim 16, wherein the PFC frame identifies that the network device port is congested by using a predetermined value for the priority vector of the PFC frame. ### Claim 18 (depends on 15) The one or more non-transitory computer readable storage media of claim 15, wherein the software is further operable to cause the processor to multiplex the network device port across the plurality of ports on the port extender based on a special tag. ### Claim 19 (depends on 15) The one or more non-transitory computer readable storage media of claim 15, wherein the software is further operable to cause the processor to determine that the input buffer for the network device port is overloaded based on an amount of data in the input buffer. ### Claim 20 (depends on 15) The one or more non-transitory computer readable storage media of claim 15, wherein the software is further operable to cause the processor to determine that the input buffer for the network device port is overloaded based on a rate of information filling the input buffer.