Timestamp Tag for Network Latency Measurement
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Solution Overview
Problem
In data center networks, measuring latency is challenging due to the difficulty in tracking packet transmission times across multiple networking devices, which hinders visibility and scalability, especially in time-sensitive applications.
Innovation Solution
Implementing a timestamp tag (TTAG) within packets that are synchronized across network devices, allowing for latency measurements and operations such as inserting, overwriting, or adding additional timestamp values, enabling precise latency tracking across the network domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If packets are temporarily stored in network buffers during transmission, then network devices can process packets at different rates, but latency measurement becomes difficult and time-sensitive applications lose visibility into packet transmission times
Solution Approach 1:
The patent applies preliminary action by inserting timestamp information into packets at the moment they enter network buffers, before any processing or forwarding occurs. This pre-timestamping approach ensures that the original transmission time is captured even though the packet will be temporarily stored and processed at different rates by subsequent network devices. The timestamp is embedded in the packet header using standard protocols like IEEE 802.1p, allowing end-to-end latency measurement without interfering with normal buffer operations.
2Measurement precision
If network devices are time synchronized with a common time reference, then accurate latency measurement becomes possible, but device complexity increases due to synchronization requirements
Solution Approach 1:
The patent leverages the universality of IEEE 1588 Precision Time Protocol (PTP) by making all network devices in the domain PTP-compliant. This single synchronization standard serves multiple purposes: it provides common time reference for accurate timestamping, enables latency measurement across different device types (switches, routers, firewalls), and works with existing packet handling mechanisms. By making the synchronization system universal rather than application-specific, the patent reduces overall complexity while maintaining measurement precision.
3Loss of information
If timestamp tags are inserted into every packet, then end-to-end latency visibility is achieved, but network bandwidth is consumed by additional packet data
Solution Approach 1:
The patent uses copying by embedding timestamp information directly into existing packet headers using standard field locations (such as IEEE 802.1p priority fields or IP header options) rather than adding separate timestamp packets or significant overhead. The timestamp data is copied into these existing structures, allowing latency information to be carried along with the original packet data without requiring additional bandwidth allocation. This approach captures complete end-to-end latency information while consuming minimal network resources.
Data Source
AI summary
Techniques are presented herein to facilitate latency measurements in a networking environment. A first network device receives a packet for transport within a network domain that comprises a plurality of network devices. The plurality of network devices have a common time reference, that is, they are time synchronized. The first network device generates timestamp information indicating time of arrival of the packet at the first network device. The first network device inserts into the packet a tag that comprises at least a first subfield and a second subfield. The first subfield comprising a type indicator to signify to other network devices in the network domain that the tag includes timestamp information, and the second subfield includes the timestamp information. The first network device sends the packet from to into the network domain to another network device. Other network devices which receive that packet can make latency measurements.