# US 2026/0074985 A1 · Handling CPU-Bound Packets in Multi-Chassis Systems During Hitless Reboot > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2026/0074985 A1 - Document ID: US20260074985A1 - Status: Published application - Kind: A1 - Application number: 18/883,160 - Filed: 2024-09-12 - Published: 2026-03-12 - Earliest claimed: 2024-09-12 - Assignees: Arista Networks, Inc. - Applicants: Arista Networks, Inc. - Inventors: Akhil SHASHIDHAR; Anand NARAYANAN; Pavan NARASIMHAPRASAD; Qing YANG - Web page: https://patentgrep.com/patent/US20260074985A1 ## CPC - H04L 45/245: {Link aggregation, e.g. trunking} - H04L 45/44: Distributed routing - H04L 45/745: Address table lookup; Address filtering - H04L 61/103: across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP] - H04L 2101/622: Layer-2 addresses, e.g. medium access control [MAC] addresses - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In one set of embodiments, at the time the control plane of a peer in a multi-chassis system is shut down as part of a hitless reboot, the peer can identify one or more rules programmed in its data plane that (1) are configured on an ingress interface of a multi-chassis link aggregation group (MLAG) to which the peer is connected, and (2) specify a central processing unit (CPU) of the peer as a destination for matched network traffic. The peer can then change each identified rule to specify an inter-chassis link between the peer and another peer in the multi-chassis system, rather than the CPU of the peer, as the destination for matched network traffic. ## Claims ### Claim 1 A method performed by a peer in a plurality of peers comprising a multi-chassis system, the method comprising, at a time of shutting down a control plane of the peer for a hitless reboot: identifying one or more rules programmed in a data plane of the peer that: are configured on an ingress interface of a multi-chassis link aggregation group (MLAG) to which the peer is connected; and specify a central processing unit (CPU) of the peer as a destination for matched network traffic; and for each of the identified rules, changing the rule to specify an inter-chassis link between the peer and another peer in the plurality of peers as the destination for matched network traffic. ### Claim 2 (depends on 1) The method of claim 1 wherein the identified rules further include a match field of source Media Access Control (MAC) address and a match value corresponding to a virtual MAC address of the multi-chassis system. ### Claim 3 (depends on 1) The method of claim 1 wherein the identified rules further include a match field of packet type and a match value indicative of Address Resolution Protocol (ARP). ### Claim 4 (depends on 1) The method of claim 1 wherein while the control plane of the peer is down during the hitless reboot, the data plane of the peer: receives a network packet matching one of the identified rules; and sends the network packet out on the inter-chassis link to said another peer, without sending the network packet to the CPU of the peer. ### Claim 5 (depends on 4) The method of claim 4 wherein the network packet is a control plane protocol packet. ### Claim 6 (depends on 5) The method of claim 5 wherein the network packet is an ARP refresh reply. ### Claim 7 (depends on 6) The method of claim 6 wherein the ARP refresh reply was sent by a device communicatively coupled with the multi-chassis system via the MLAG. ### Claim 8 (depends on 7) The method of claim 7 wherein the ARP refresh reply was sent by the device in response to an ARP refresh request originating from said another peer. ### Claim 9 (depends on 1) The method of claim 1 further comprising, at a time the control plane of the peer is booted up as part of the hitless reboot: reverting the identified rules to once again specify the CPU of the peer as the destination of matched network traffic. ### Claim 10 A network device that is part of a multi-chassis system comprising a plurality of network devices, the network device comprising: a data plane; and a control plane including a central processing unit (CPU) and a main memory, the main memory having stored thereon program code that when executed by the CPU causes the CPU to, at a time of shutting down the control plane for a hitless reboot: identify one or more rules programmed in the data plane that: are configured on an ingress interface of a multi-chassis link aggregation group (MLAG) to which the network device is connected; and specify the CPU as a destination for matched network traffic; and for each of the identified rules, change the rule to specify an inter-chassis link between the network device and another network device in the plurality of network devices as the destination for matched network traffic. ### Claim 11 (depends on 10) The network device of claim 10 wherein the identified rules further include a match field of source Media Access Control (MAC) address and a match value corresponding to a virtual MAC address of the multi-chassis system. ### Claim 12 (depends on 10) The network device of claim 10 wherein the identified rules further include a match field of packet type and a match value indicative of Address Resolution Protocol (ARP). ### Claim 13 (depends on 10) The network device of claim 10 wherein while the control plane is down during the hitless reboot, the data plane: receives a network packet matching one of the identified rules; and sends the network packet out on the inter-chassis link to said another network device, without sending the network packet to the CPU. ### Claim 14 (depends on 13) The network device of claim 13 the network packet is a control plane protocol packet. ### Claim 15 (depends on 14) The network device of claim 14 wherein the network packet is an ARP refresh reply. ### Claim 16 (depends on 15) The network device of claim 15 wherein the ARP refresh reply was sent by a device communicatively coupled with the multi-chassis system via the MLAG. ### Claim 17 (depends on 16) The network device of claim 16 wherein the ARP refresh reply was sent by the device in response to an ARP refresh request originating from said another network device. ### Claim 18 (depends on 10) The network device of claim 10 wherein the program code further causes the CPU to, at a time the control plane is booted up as part of the hitless reboot: revert the identified rules to once again specify the CPU as the destination of matched network traffic. ### Claim 19 A method performed by a peer in a plurality of peers comprising a multi-chassis system, the method comprising, at a time of shutting down a control plane of the peer: identifying one or more rules that: are configured on an interface of a multi-chassis link aggregation group (MLAG) which the peer is a part of; and specify a central processing unit (CPU) of the peer as a destination for matched network traffic; and for each of the identified rules, changing the rule to forward network traffic matching the rule to another peer in the plurality of peers rather than to the CPU. ### Claim 20 (depends on 19) The method of claim 19 wherein the control plane of the peer is shut down as part of a hitless reboot process.