5. Use Cases

This section preserves the RFC text for IPFIX delay performance metric export, including On-Path Telemetry, OAM nodes, Flow Records, performance metric IDs 27-30, IPFIX Information Elements 530-533, IANA registrations, operational guidance, and encoding examples.

Original RFC Text

5.  Use Cases

   The measured On-Path delay can be aggregated with Flow Aggregation as
   defined in [RFC7015] across the following device and control-plane
   dimensions [IANA-IPFIX] to determine:

   *  With node id and egressInterface(14), on which node which logical
      egress interfaces have been contributing to how much delay.

   *  With node id and egressPhysicalInterface(253), on which node which
      physical egress interfaces have been contributing to how much
      delay.

   *  With ipNextHopIPv4Address(15) or ipNextHopIPv6Address(62), the
      forwarding path to which next-hop IP contributed to how much
      delay.

   *  With mplsTopLabelIPv4Address(47) or destinationIPv6Address and
      srhActiveSegmentIPv6(495), the forwarding path to which MPLS top-
      label IPv4 address or IPv6 destination address and Segment Routing
      over IPv6 (SRv6) active segment contributed to how much delay.

   *  BGP communities [RFC1997] are often used for setting a path
      priority or service selection.  With
      bgpDestinationExtendedCommunityList(488) or
      bgpDestinationCommunityList(485) or
      bgpDestinationLargeCommunityList(491), which group of prefixes
      accumulated at which node how much delay.

   *  With destinationIPv4Address(13), destinationTransportPort(11),
      protocolIdentifier(4), and sourceIPv4Address(8), or equivalent
      IPFIX IEs for IPv6, the forwarding path delay on each node from
      each IPv4 source address to a specific application in the network.

   Let us consider Figure 1 as a topology example.  Table 2 shows the
   aggregated delay per each node, ingressInterface(10),
   egressInterface(14), destinationIPv6Address(28), and
   srhActiveSegmentIPv6(495) measured at ingress.

   +===========+===========+======+=============+=============+=======+
   | ingress   | egress    | Node | destination | srhActive   | Path  |
   | Interface | Interface |      | IPv6Address | SegmentIPv6 | Delay |
   +===========+===========+======+=============+=============+=======+
   | 271       | 276       | R0   |             |             | 0 µs  |
   +-----------+-----------+------+-------------+-------------+-------+
   | 301       | 312       | R1   | 2001:db8::1 | 2001:db8::3 | 22 µs |
   +-----------+-----------+------+-------------+-------------+-------+
   | 22        | 27        | R2   | 2001:db8::2 | 2001:db8::3 | 42 µs |
   +-----------+-----------+------+-------------+-------------+-------+
   | 852       | 854       | R3   | 2001:db8::3 | 2001:db8::3 | 122   |
   |           |           |      |             |             | µs    |
   +-----------+-----------+------+-------------+-------------+-------+

      Table 2: Example Table of Measured Delay at Ingress, Ascending
                                 by Delay