sFlow.org Chen Rozenbaum https://sFlow.org/ Broadcom Corp. info@sflow.org Peter Phaal InMon Corp. November 2020 sFlow Transit Delay Structures Copyright Notice Copyright (C) sFlow.org (2020). All Rights Reserved. Abstract This memo describes an sFlow version 5 structure for exporting information about packet transit delay. Table of Contents 1. Overview ...................................................... 1 2. sFlow Datagram Extension ...................................... 1 3. References .................................................... 2 4. Author's Addresses ............................................ 2 1. Overview This document describes additional structures that allow an sFlow agent to export information about transit delay that a sampled packet packet experiences as it traverses a switching device. sFlow version 5 is an extensible protocol that allows the addition of new data structures without impacting existing collectors. This document does not change the sFlow version 5 protocol [1], it simply defines additional, optional, data structures that a network device can use to export packet transit delay information in sFlow. 2. sFlow Datagram Extension Transit delay is the time the sampled packet spent in the Network Device. Queue depth is the number of bytes already in the selected output queue when the sampled packet is enqueued. The extended_delay structure defined in this document can be added to a flow_sample [1] to report transit delay and queue depth for the DRAFT sFlow.org [Page 1] Version 0.2 sFlow Transit Delay Structure November 2020 sampled packet. The flow_sample input and output interface fields identify the path through the network device. An extended_egress_queue structure [2] should be included to identify the selected egress queue. /* Delay for sampled packet traversing switch */ /* extended_egress_queue structure must be included */ /* opaque = flow_data; enterprise = 0; format = 1039 */ struct extended_delay { unsigned int transit; /* transit delay in nanoseconds 0xffffffff indicates value >= 0xffffffff */ unsigned int queue; /* queue depth in bytes */ } 3. References [1] Phaal, P. and Lavine, M., "sFlow Version 5", https://sflow.org/sflow_version_5.txt, July 2006 [2] Schimmel, A., Roulin, A. and Phaal, P., "sFlow Dropped Packet Noti- fication Structures", https://sflow.org/sflow_drops.txt, October 2020 4. Author's Address Chen Rozenbaum Broadcom Corp. EMail: chen.rozenbaum@broadcom.com Peter Phaal InMon Corp. 1 Sansome Street, 35th Floor San Francisco, CA 94104 EMail: peter.phaal@inmon.com DRAFT sFlow.org [Page 2]