Page 193 - ITU-T Focus Group IMT-2020 Deliverables

ITU-T Focus Group IMT-2020 Deliverables 3

A FlexE-enabled network must support the following performance measurements on their Ethernet
interfaces according to Section 8 of ITU-T G.8013/Y.1731 [Ref. Appendix II-1]:
• Frame loss measurement.
• Frame delay measurement.

• Frame delay throughput measurement.
A FlexE-enabled network must support the following fault management according to Section 7 of ITU-T
G.8013/Y.1731 [Ref. Appendix II-1]:
• Ethernet continuity check
• Ethernet loopback
• Ethernet link trace
• Ethernet alarm indication signal

• Ethernet remote defect indication
• Ethernet locked signal
• Ethernet test signal
Because FlexE connections are contained logically within Ethernet PHYs, the Ethernet OAM functions can be
used to assist with SLA assurance, capacity planning, performance monitoring, and diagnostic analysis for
FlexE connections as well. In addition, some Ethernet OAM events (e.g., alarm signals) must be propagated
to the relevant FlexE shim layer so proper actions can be taken.

Additional OAM functions are required in FlexE-enabled networks, as elaborated in the following sections.

II.2.1 FlexE Neighbor Discovery
There requires an automatic discovery mechanism between two devices (routers or switches) that are
interconnected. The information that needs to be made known to the two interconnected devices for FlexE
to operate include FlexE group ID, PHY number, capability of shim entity, mux and demux functions, etc.
Manual configuration is recommended in as a general approach. For better scaling in operation and
management, an automatic discovery and connectivity verification mechanism is more promising in
proposals including those in [Ref. Appendix II-2] and [Ref. Appendix II-3].

II.2.2 FlexE End-to-End Connection Connectivity Verification
For an end-to-end FlexE Connection, there requires an OAM tool for fault detection and diagnostic
mechanisms that can be used for end-to-end fault detection and diagnostics. Using this tool, the two ends of
a FlexE connection can exchange ping-alike messages to assure the connection is operational with healthy
status and integrity. Note this communication must be in-band with the FlexE connection.

II.3 FlexE-3 Resizing of FlexE Connection
A FlexE connection (or channel for that matter) is associated with a fixed MAC rate. Due to dynamic nature
of business environment, user experiences, evolvement of applications, etc., the bandwidth of a FlexE client
actually in use may vary, sometimes is smaller but other time require bigger than the MAC rate of the relevant
FlexE connection. For the former case, a separate FlexE connection with smaller MAC rate is desirable so that
the unused bandwidth out of the associated Ethernet PHYs can be assigned to other applications and users.
For the latter case, a separate FlexE connection with larger MAC rate is required. The operation that moves
FlexE client from an existing FlexE connection to another that has either smaller or larger MAC rate is called
resizing of FlexE connection. Figure Appendix-FlexE-2 illustrates an example where a FlexE connection of 50G
MAC rate can be either resized to another one of 75G MAC rate (upsizing) or 25G MAC rate (downsizing).

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