[RPRWG] RE: new shaper text
John,
Relative to your email and suggested change to the
shaper text.
I will be voting against these changes, for reasons
listed below. I hope that you will clearly document
this lack of consensus when discussing your revisions
with other working group members.
What's up? You ask my opinion, I present concerns with
unwritten/verbal Cisco change proposals, and implement
as Cisco suggested. This process does not lead towards
consensus, a goal of the IEEE standardization process.
DVJ
>>Removed source shaper: Not necessary. Can be done beyond the
>>scope of the standard.
By making this decision, you have effectively
allowed the ringlet-circulation time for class-B
and class-C traffic to become unbounded.
As we noted, Mike Takefman previously acknowledge
this was not a good idea, and Cisco had experienced
problems in the field with this specific problem.
The working group needs, as we discussed previously,
to be involved in deciding whether:
1) Class-B/C traffic has a bounded ringlet
circulation time (this has been the written
BAH proposal for over 3 months).
2) Class-B/C traffic has an unbounded ringlet
circulation time.
(this was apparently Cisco's input to you)
Having an unbounded lifetime also breaks some algorithms
that rely on finite lifetimes, including those being
considered by the BAH. And, it violates the guaranteed
bandwidth properties that class-B traffic would otherwise
have.
>>Removed resets. Credits should be allowed to grow up
>>to the limit specified. Burst control is specified
>>by upper limit.
By making this decision, you have effectively increased
the guaranteed class-A latency from N*MTU to N*N*MTU,
as we had noted in previous discussions of whether
this Cisco proposed change should be adopted.
The working group needs, as we discussed previously,
to be involved in deciding whether:
1) Class-A has an N*MTU latency guarantee
(this has historically been the BAH decision)
2) Class-A is optimized for bursty traffic throughput,
a property previously assumed only for classB.
(this was apparently Cisco's input to you)
This is what ad-hoc and working groups are for:
I suggest that a group decision is needed on this
one also.
DVJ
David V. James
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Base: dvj@xxxxxxxxxxxx
>>-----Original Message-----
>>From: JLemon@xxxxxxxxxxxx [mailto:JLemon@xxxxxxxxxxxx]
>>Sent: Tuesday, September 24, 2002 7:00 PM
>>To: dvj@xxxxxxxxxxxx
>>Subject: new shaper text
>>
>>
>>David,
>>
>>Attached is my latest version of the shaper text. I made the
>>following changes:
>>
>>Removed source shaper: Not necessary. Can be done beyond the
>>scope of the standard.
>>
>>Removed resets. Credits should be allowed to grow up to the limit
>>specified. Burst control is specified by upper limit.
>>
>>Finished incorporating tying of Clause 6 and Clause 9. See
>>especially 6.6.4 and 6.7.5.
>>
>>Lots of miscellaneous updates.
>>
>>jl
>>
>> <<jl_cls06_MAC_6.6_0924.pdf>>
>>