3. Management Considerations

This section preserves the RFC text for the DLEP IEEE 802.1Q Aware Credit Window extension, including Extension Type 5, VLAN identifiers, PCPs, traffic classification, credit windows, IANA registration, and normative behavior.

Original RFC Text

3.  Management Considerations

   This section provides several network management guidelines for
   implementations supporting the IEEE 802.1Q Aware Credit Window
   Extension.

   If this extension is supported, that support MUST be declared using
   the Extensions Supported Data Item (see Section 13.6 of [RFC8175]),
   which is configurable on both modems and routers.  Diffserv Aware
   Credit Window Extension Data Items MUST NOT be emitted by a DLEP
   participant unless such support was specified in the initialization
   message received from its peer.  The use of the extension defined in
   this document SHOULD be configurable on both modems and routers.

   Modems SHOULD support the configuration of mapping a PCP to a credit
   window (queue).

   Modems MAY support the configuration of mapping a PCP to a credit
   window (queue) on a per-VLAN basis.  VID value zero (0x0000) is used
   by [RFC9892] to indicate that the VID is ignored.  VID 0xFFFF is
   reserved.  Any other VID value from 0x0001 through 0xFFFE can be used
   in traffic classification.

   When VLANs are supported by a modem without support from PCPs, the
   modem SHOULD support the configuration of mapping a VLAN to a credit
   window (queue).

   Modems MAY support the configuration of the number of credit windows
   (queues) that they advertise to a router.

   Routers may impose limitations on the number of queues they can
   support and on the allowable credit window configurations.  In some
   cases, per-destination queues may not be supported.  If the credit
   window information provided by the modem exceeds the router's
   capabilities, the router SHOULD utilize a subset of the advertised
   credit windows.  Alternatively, the router MAY reset the session and
   indicate that the extension is not supported.  In either case, any
   mismatch in capabilities SHOULD be reported to the user through
   standard network management mechanisms, such as user interface
   notifications or error logging.

   Regardless of implementation, if credit windows are in use, the
   router MUST NOT send traffic to the modem unless sufficient credits
   are available.