Subject: [ipcdn] docsQosServiceFlowPolicedDropPkts

From: "Margo Dolas" <[email-masked]>
Date: Mon, 26 Feb 2001 16:18:04 -0500

The docsQosServiceFlowPolicedDropPkts entry says:
"The number of packets dropped due to policing of the service flow,
especially to limit the maximum rate of the flow."

Dropped packets can occur in the following cases:
  1. Would exceed max rate.
  2. Would exceed max burst.
  3. Exceeds UGS grant size.
  4. Insufficient h/w or other resources to send packet.

Should this mib be (maxRate + maxBurst)?  What about the case in which the
UGS grant size is exceeded?  (In this case, the packet will either be
dropped or sent on the primary flow, depending on the policy bits for this
flow.)

How should UGS-oversize packets be handled?  Should only dropped-UGS
oversize packets be counted?  All UGS-oversize packets?  Or should
UGS-oversize packets be ignored altogether?

Margo Dolas
Broadcom Corp.

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From: Andre Lejeune <[email-masked]>
Date: Tue, 27 Feb 2001 09:22:52 -0500

Margo,

I agree with you that the definition of docsQosServiceFlowPolicedDropPkts
is too vague and would be subject to interpretation.  The max rate exceeded
is accounted for in the docsQosServiceFlowPolicedDropPkts Mib on a per SFID
basis, but all other discards are currently only accounted for in the
ifOutDiscards Mib on a per interface basis.

I believe that the aggregate counter ifOutDiscards is useful to determine
if there is a problem with a CM. Following this, specific counters are
needed to pin down the problem. Aggregating more "drop" conditions in
the docsQosServiceFlowPolicedDropPkts would only help determine which
service flow is a problem. I don't think this is sufficient. I would
prefer to see separate counters for each error conditions that may
occur.

What does the author of the qos mib think? What do MSOs think?

André