# US 12,184,549 B2 · Dynamic re-routing and modification of layer traffic in virtualized RANs > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,184,549 B2 - Document ID: US12184549B2 - Status: Granted - Kind: B2 - Application number: 17/825,645 - Filed: 2022-05-26 - Published: 2023-11-30 - Granted: 2024-12-31 - Earliest claimed: 2022-05-26 - Assignees: Microsoft Technology Licensing, LLC - Applicants: Microsoft Technology Licensing, LLC - Inventors: Anuj Kalia; Daehyeok Kim; Ilias Marinos; Tao Ji; Nikita Lazarev; Paramvir Bahl - Web page: https://patentgrep.com/patent/US12184549B2 ## CPC - H04L 45/28: using route fault recovery - H04L 45/76: Routing in software-defined topologies, e.g. routing between virtual machines - H04L 45/22: {Alternate routing} - H04W 40/34: Modification of an existing route - H04L 49/552: by ensuring the integrity of packets received through redundant connections - H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Methods and systems for dynamically re-routing layer traffic between different servers with little user-visible disruption and without modifications to the vRAN software stack are provided. This approach enables operators to initiate a PHY migration either on demand (e.g., during planned maintenances) or to set up automatic migration on unexpected events (e.g., server failures). It is recognized that PHY processing in cellular networks has no hard state that must be migrated. As a result, layer traffic such as the PHY-L2 traffic or L2-PHY traffic can be simply re-routed to a different server. This re-routing mechanism is realized by interposing one or more message controllers (e.g., middlebox) in a communication channel between the PHY and L2. ## Claims ### Claim 1 A server system supporting a radio access network (RAN), comprising: a first message controller associated with a first RAN server; and memory storing instructions that, when executed by a processor, cause the first message controller to perform a set of operations, the set of operations comprising: intercepting a first message from a first layer one (PHY) of the first RAN server, wherein the first message is directed to a first layer two (L2) of the first RAN server over a first communication channel; converting the first message into one or more first network packets, wherein converting the first message into the one or more first network packets comprises dropping state information of the first layer one PHY associated with at least one slot; and re-routing the first message to a second layer two (L2) of a second RAN server by transmitting the one or more first network packets at a slot boundary via a network. ### Claim 2 (depends on 1) The server system of claim 1, wherein the first communication channel is a shared-memory channel. ### Claim 3 (depends on 1) The server system of claim 1, wherein the first layer one PHY processes data for a cell tower of the RAN, and wherein the first message comprises processed data associated with the cell tower. ### Claim 4 (depends on 1) The server system of claim 1, wherein: the first message is received by a second message controller associated with the second RAN server; and the first message is placed in a second communication channel associated with the second L2 in the second RAN server. ### Claim 5 (depends on 4) The server system of claim 4, wherein: a second message is intercepted by the second message controller, wherein the second message is directed from the second L2 in the second RAN server to a second PHY in the second RAN server; the second message is converted by the second message controller into one or more second network packets; and the second message is re-routed by the second message controller to the first layer one PHY of the first RAN server by transmitting the one or more second network packets via the network. ### Claim 6 (depends on 5) The server system of claim 5, wherein the first and second messages are femtocell application programming interface (FAPI)-compliant messages. ### Claim 7 (depends on 1) The server system of claim 1, wherein the first RAN server is different from the second RAN server. ### Claim 8 A method of re-routing a message from a first RAN server to a second RAN server of a radio access network (RAN), comprising: placing, by a PHY processor in the first RAN server, the message in a first memory of the first RAN server; converting, by a first message controller in the first RAN server, the message in the first memory into one or more network packets, wherein converting the message into the one or more network packets comprises dropping state information of the PHY processor for at least one slot; and re-routing, by the first message controller, the one or more network packets to a second message controller in the second RAN server at a slot boundary via a network. ### Claim 9 (depends on 8) The method of claim 8, wherein the second message controller stores the message in a second memory of the second RAN server. ### Claim 10 (depends on 9) The method of claim 9, wherein a second L2 processor of the second RAN server accesses the message in the second memory. ### Claim 11 (depends on 8) The method of claim 8, wherein the PHY processor is responsible for processing data for a cell tower of a radio access network (RAN), and wherein the first message comprises processed data associated with the cell tower. ### Claim 12 (depends on 11) The method of claim 11, wherein the first memory is shared between the PHY processor and a first L2 processor on the first RAN server. ### Claim 13 (depends on 12) The method of claim 12, wherein the second memory is shared between a second PHY processor and the second L2 processor on the second RAN server. ### Claim 14 A method of re-routing a message from a first RAN server to a second RAN server of a radio access network (RAN), comprising: intercepting, by a first message controller in the first RAN server, the first message from a first layer one (PHY) in the first RAN server to a first layer two (L2) in the first RAN server over a communication channel; converting, by the first message controller, the first message into one or more first network packets, wherein converting the first message into the one or more first network packets comprises dropping state information of the first layer one PHY associated with at least one slot; and re-routing, by the first message controller, the first message to a second layer two (L2) of a second RAN server by transmitting the one or more first network packets at a slot boundary via a network. ### Claim 15 (depends on 14) The method of claim 14, wherein the communication channel is a shared-memory channel. ### Claim 16 (depends on 14) The method of claim 14, wherein the first layer one PHY processes data for a cell tower of the RAN, and wherein the first message comprises processed data associated with the cell tower. ### Claim 17 (depends on 14) The method of claim 14, wherein: the first message is received by a second message controller associated with the second RAN server; and the first message is placed in a second communication channel associated with the second L2 in the second RAN server. ### Claim 18 (depends on 17) The method of claim 17, wherein: a second message is intercepted by the second message controller, wherein the second message is directed from the second L2 in the second RAN server to a second PHY in the second RAN server; the second message is converted by the second message controller into one or more second network packets; and the second message is re-routed by the second message controller to the first layer one PHY of the first RAN server by transmitting the one or more second network packets via the network. ### Claim 19 (depends on 18) The method of claim 18, wherein the first and second messages are femtocell application programming interface (FAPI)-compliant messages. ### Claim 20 (depends on 14) The method of claim 14, wherein the first RAN server is different from the second RAN server.