Round trip time (RTT) measurement based upon sequence number

Patent metadata

Field	Value
Publication number	US-12596568-B2
Application number	US-202418415160-A
Country	US
Kind code	B2
Filing date	Jan 17, 2024
Priority date	Jun 5, 2015
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

Systems, methods, and computer-readable media are provided for determining a packet's round trip time (RTT) in a network. A system can receive information of a packet sent by a component of the network and further determine an expected acknowledgement (ACK) sequence number associated with the packet based upon received information of the packet. The system can receive information of a subsequent packet received by the component and determine an ACK sequence number and a receiving time of the subsequent packet. In response to determining that the ACK sequence number of the subsequent TCP packet matches the expected ACK sequence number, the system can determine a round trip time (RTT) of the packet based upon the received information of the packet and the received information of the subsequent packet.

First claim

What is claimed is:

1 . A method comprising:
determining, at a network device in a network, an expected acknowledgement (ACK) sequence number associated with a packet; determining an ACK sequence number of a different packet; when the ACK sequence number of the different packet does not match the expected ACK sequence number, ignoring the different packet; determining that an ACK sequence number of another packet; and when the ACK sequence number of the another packet matches the expected ACK sequence number, determining a round trip time (RTT) of the packet.

2 . The method of claim 1 , further comprising:
generating a warning when the ACK sequence number of the different packet does not match the expected ACK sequence number.

3 . The method of claim 1 , further comprising:
determining an additional expected ACK sequence number associated with an additional packet sent by a device in the network; determining that an additional ACK sequence number of a different additional packet received by the device matches the additional expected ACK sequence number associated with the additional packet; and determining a round trip time (RTT) of the additional packet based on first information of the additional packet and second information of the different packet.

4 . The method of claim 3 , further comprising:
receiving third information corresponding to a transmission control protocol (TCP) handshake performed within a specific time period and associated with a TCP connection; and based on the third information corresponding to the TCP handshake, determining a number of at least one of re-transmission packets and new packets transmitted during the specific time period.

5 . The method of claim 1 , wherein the expected ACK sequence number is determined based on a third ACK sequence number of the packet and a size of the packet.

6 . The method of claim 1 , further comprising:
determining a sending time, a packet sequence number and a packet size of the packet based on packet information sensed by at least one sensor of a plurality of sensors in the network, the packet information corresponding to the packet.

7 . The method of claim 6 , further comprising:
determining a receive time of a subsequent packet received by a device associated with the network; and determining the round trip time (RTT) of the packet based on the sending time of the packet and the receive time of the subsequent packet.

8 . The method of claim 1 , further comprising:
determine a respective ACK sequence number of a following packet based on first packet information of the following packet; and in response to a determination that the respective ACK sequence number of the following packet matches a second expected ACK sequence number, determining a round trip time (RTT) of the packet based on second packet information of the packet and the first packet information of the following packet.

9 . The method of claim 1 , further comprising:
determining a congestion level of the network based at least on the round trip time (RTT) of the packet.

10 . The method of claim 1 , further comprising:
determining a number of non-duplicative packets; and determining a packet loss rate of the network during a time period based at least on the number of non-duplicative packets.

11 . A system comprising:
one or more processor; and a computer-readable storage medium storing instructions which, when executed by the one or more processor, cause the system to:
determine an expected acknowledgement (ACK) sequence number associated with a packet in a network;
determine an ACK sequence number of a different packet;
when the ACK sequence number of the different packet does not match the expected ACK sequence number, ignore the different packet;
determine that an ACK sequence number of another packet; and
when the ACK sequence number of the another packet matches the expected ACK sequence number, determine a round trip time (RTT) of the packet.

12 . The system of claim 11 , wherein the instructions, when executed by the one or more processor, cause the system to:
select a range of packet sequence numbers; determine a packet sequence number of the packet based on packet information of the packet; and determine that the packet sequence number of the packet is within the range of packet sequence numbers.

13 . The system of claim 11 , wherein the instructions, when executed by the one or more processor, cause the system to:
generate a warning when the ACK sequence number of the different packet does not match the expected ACK sequence number.

14 . The system of claim 11 , wherein the instructions, when executed by the one or more processor, cause the system to:
determine an additional expected ACK sequence number associated with an additional packet sent by a component associated with the network; determine that an additional ACK sequence number of a different additional packet received by the component matches the additional expected ACK sequence number associated with the additional packet; and determine a round trip time (RTT) of the additional packet based on first information of the additional packet and second information of the different additional packet.

15 . The system of claim 14 , wherein the instructions, when executed by the one or more processor, cause the system to:
receive third information corresponding to a transmission control protocol (TCP) handshake performed within a specific time period and associated with a TCP connection; and based on the third information corresponding to the TCP handshake, determine a number of at least one of re-transmission packets and new packets transmitted during the specific time period.

16 . The system of claim 11 , wherein the expected ACK sequence number is determined based on an additional ACK sequence number of the packet and a size of the packet.

17 . The system of claim 11 , wherein the instructions, when executed by the one or more processor, cause the system to:
determine a sending time, a packet sequence number and a packet size of the packet based on packet information sensed by at least one sensor of a plurality of sensors in the network, the packet information corresponding to the packet; determine a receive time of a further packet received by a component associated with the network; and determine the round trip time (RTT) of the packet based on the sending time of the packet and the receive time of the further packet.

18 . The system of claim 11 , wherein the instructions, when executed by the one or more processor, cause the system to:
determine a number of non-duplicative packets; and determine a packet loss rate of the network during a time period based at least on the number of non-duplicative packets.

19 . The system of claim 11 , wherein the expected ACK sequence number is determined independent of the different packet.

20 . A non-transitory computer-readable medium having stored thereon instructions which, when executed by one or more processor, cause the one or more processor to:
determine an expected acknowledgement (ACK) sequence number associated with a packet; determine an ACK sequence number of a different packet; when the ACK sequence number of the different packet does not match the expected ACK sequence number, ignore the different packet; determine that an ACK sequence number of another packet; and when the ACK sequence number of the another packet matches the expected ACK sequence number, dete

Assignees

• Cisco Tech Inc

Inventors

• Attar Mohammadreza
• Yadav Navindra
• Singh Abhishek Ranjan
• Jeyakumar Vimalkumar
• Gandham Shashidhar
• Spadaro Roberto Fernando

Classifications

• G06F16/2365

  Ensuring data consistency and integrity · CPC title

• H04L45/306

  Route determination based on the nature of the carried application · CPC title

• H04L63/1466

  Active attacks involving interception, injection, modification, spoofing of data unit addresses, e.g. hijacking, packet injection or TCP sequence number attacks · CPC title

• H04L69/16

  Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP] · CPC title

• H04L47/28

  in relation to timing considerations · CPC title