ONL Tutorial

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QIDs

The QMGR supports 512 queues. Queues are identified by their Queue Identifiers (QIDs). There are 127 queues destined for the SPC, 127 queues returning from the SPC, 8 ingress datagram queues, 64 egress datagram queues, and 184 other reserved flow queues shared between the ingress and egress sides of each port. The QID assignments are:

1 - 127: To the SPC (1-7 are FPX reserved SPC queues; the SPC software only uses 8-127)
128 - 255: From SPC (internal to the QMGR and not software configurable)
256 - 439: Reserved flow queues
440 - 503: Line card (egress) datagram queues
504 - 511: Switch (ingress) Virtual Output Queues (VOQs)

The QMGR can be configured to either assign fixed pacing rates to ingress VOQs or dynamic pacing rates based on a Distributed Queueing algorithm that attempts to avoid both egress queue overflow and underflow (underutilization). The rate to the SPC is paced at no more than 200 Mb/s.

Fig. 1. The Queue Manager.

Revised: Thu, July 13, 2006

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