RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc meeting
Devendra,
your proposal looks interesting and, for me, this is an improvement of
the "promiscous mode" idea originally proposed in Alladin.
I know that this proposal has been strongly criticized because it
violates the layering principles and this seems not acceptable in IEEE.
I do not have any idea on why this time there were no reactions.
Regards, Italo
> -----Original Message-----
> From: tripathi@xxxxxxxxxxxxx [mailto:tripathi@xxxxxxxxxxxxx]
> Sent: Thursday, March 28, 2002 2:23 AM
> To: raj@xxxxxxxxxxxx; hpeng@xxxxxxxxxxxxxxxxxx
> Cc: tripathi@xxxxxxxxxxxxx; stds-802-17@xxxxxxxx
> Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc meeting
>
>
> Hi team,
Looks if my response to Mike's earlier mail was not noticed as everyone
is talking about the deciding the buffer size to
guarantee a loss less ring. I would like to repeat the option I
suggested in that mail.
Basically the packets which can not be delivered by MAC within a
certain time for a given priority could be sent to upper layer
as "packets in waiting". Since MAC can not be expected to maintains
flows, and out of order packets have to be avoided,
once a packet of a certain priority goes on the path of "packets in
waiting", the MAC will have to keep on sending all packets
of that priority to upper layer till "Waiting Queue Empty" indication
comes from upper layer. Also, as I mentioned in previous
mail, it would be possible for a MAC to emulate the behavior of this
upper layer by having suitable size of buffer or allow for
loss, but then it would be implementation detail and standard would not
have to worry about it.
The buffer size option is not scalable one and it will be very
contentious issue (at least for a MAC).
Regards,
Devendra Tripathi
CoVisible Solutions, Inc
(In India: VidyaWeb (India) Pvt Ltd)
90 Great Oaks Blvd #206
San Jose, Ca 95119
Tel: (408)226-6800,
Fax: (408)226-6862
-----Original Message-----
From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
[mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of
Raj Sharma
Sent: Wednesday, March 27, 2002 4:43 PM
To: 'Harry Peng'; Raj Sharma
Cc: stds-802-17@xxxxxxxx
Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc meeting
Harry,
I am not suggesting a lossy ring. I requested one, but most of you
convinced
me that will never happen in RPR. So, I am moving on with an
assumption of
a loss less RPR ring and I request you do too.
However, if I were to uphold the argument for a loss less ring
while absolutely
guaranteeing no priority inversion than
a certain size of LPTB buffer must designed in. Obviously the size
of this
LPTB depends on the levels of HP traffic and the RTT. Everything
has a
consequence - there is no freee lunch !
So, the corollary, that if the LPTB size is fixed on the ring than
for a given
ring circumference only a certain level of HP traffic, with
absolute guarantees
on jitter, can be provided. This implies that carriers would have
to predict
the levels of HP traffic in the network before they procure their
equipment.
The one way to resolve this problem is to be able to "add" more
LPTB
to the RPR MAC to sustain higher levels of HP traffic on the ring.
Unfortunately,
at 10 gbps speeds off-chip TB schemes will have significant
penalties.
Anyway, you missed my statement I made in the original email.
I said that if one were to prevent packet loss and avoid priority
inversion
than one must AVOID situations that creates a scenario to pick one
over the other. Somehow, that seems like a simple logic to me. So,
my argument was not for supporting a lossy ring but what you need
to
in order to have a loss less ring and avoid priority inversion.
In fact, I wonder why you don't think similar since your
requirement is to
have a loss less ring, no priority inversion and a single 2 MTU
TB. I would think
the a single TB with ability to buffer 2 packets cries out for
some method
to AVOID a situation that will force priority inversion to honor a
loss less ring
requirement. I must be missing something !
The real issue is that I am not fixated on preserving any
implementation at
the cost of having an absurd standard. On the other hand, I am
tolerant to the
big guns who want to do this I think we need to ensure that the
RPR WG
do diligence.
raj
-----Original Message-----
From: Harry Peng [mailto:hpeng@xxxxxxxxxxxxxxxxxx]
Sent: Tuesday, March 26, 2002 7:40 AM
To: raj@xxxxxxxxxxxx
Cc: stds-802-17@xxxxxxxx
Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc meeting
Raj:
There are really two issues
one is vendor box issues when interworking:
1) utilization versus implementation to achieve the desired
packet delivery behavior.
The 1 TB and 2 TB design fall with in this category
Once reserved BW is allocated globally or at link level,
you think your box provide
better ring BW utilization. All the power to you.
2) Lossy ring
This is an 802.17 issue.
Lossless behavior is a must. You are arguing for lossy.
Regards,
Harry
-----Original Message-----
From: Leon Bruckman [mailto:leonb@xxxxxxxxxxxxx]
Sent: Tuesday, March 26, 2002 1:59 AM
To: 'Raj Sharma'
Cc: stds-802-17@xxxxxxxx
Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
For the 2 transit buffer scheme there is another way:
Have a LPTB that is deep enough. The LPTB depth to avoid
both: "on transit"
LP traffic discard and reduced HP priority, can be
calculated using the
formula in:
http://grouper.ieee.org/groups/802/17/documents/presentations/jan2002/vk
_dwd
el_02.pdf
This formula can be modified for the case of links with
different reserved
rates also.
Leon
-----Original Message-----
From: Raj Sharma [mailto:raj@xxxxxxxxxxxx]
Sent: Tuesday, March 26, 2002 3:43 AM
To: 'Sanjay K. Agrawal'; Li Mo; stds-802-17@xxxxxxxx; Nader
Vijeh
Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
The only way to guarantee HP traffic and have no packet
loss
is to be able to AVOID situations that will reduce the
priority
of HP traffic to satisfy a loss less ring.
There are two ways to avoid:
1. Provision the low priority to ramp-up very slowly - this
will result in low link utilization.
2. Constantly, provide each node the ability to determine
what conditions would lead to congestion.
raj
> -----Original Message-----
> From: Sanjay K. Agrawal
[mailto:sagrawal@xxxxxxxxxxxxxxxxxx]
> Sent: Monday, March 25, 2002 5:03 PM
> To: Li Mo; stds-802-17@xxxxxxxx; Nader Vijeh
> Subject: Re: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
>
>
>
> For me 2 is very important otherwise I have very limited
> spatial reuse . On
> the other hand, allowing the packet loss on the ring,
will
> limit the scope
> of this technology to TCP/IP networks. I think somehow we
have to
> accommodate both.
>
> -Sanjay K. Agrawal
>
>
> ----- Original Message -----
> From: "Li Mo" <limo01@xxxxxxxxx>
> To: <stds-802-17@xxxxxxxx>; "Nader Vijeh"
<nader@xxxxxxxxxxxxxx>
> Sent: Friday, March 22, 2002 11:04 AM
> Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
>
>
>
>
> I agree with the comments made by previous authers. I
used to
> think one of
> the key characteristics of RPR is "no packet loss" once
it is
> in transport.
> But, with the different reservation rate possible on
> different spans (unless
> a very sophasticated fairness algorithm has been used
which
> is unknow at
> this time, this characteristics may be unattendable.
Hence
> we have a choice
> to be made:
>
> 1. allow the packet loss on the ring
> 2. allow different reserved rate on different span
>
> For those, I would like to see the first one unless
somebody
> developed a
> fairness algorithm which achieves both.
>
> Li...
>
> -----Original Message-----
> From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of
Nader Vijeh
> Sent: Friday, March 22, 2002 12:12 PM
> To: stds-802-17@xxxxxxxx
> Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
>
>
>
> We have customers that find loosing packets in the
transport
> side of the
> network unacceptable. One of the reasons we hear is the
"multi-tier"
> environment, where the transport and the service side may
be
> "logically"
> separate and belong to different business entities.
Another item to
> consider is that RPR is competing with SONET for the data
transport
> infrastructure and SONET does not loose packets in
transit.
>
> Nader
>
> -----Original Message-----
> From: Mike Takefman [mailto:tak@xxxxxxxxx]
> Sent: Friday, March 22, 2002 7:44 AM
> To: Italo.Busi@xxxxxxxxxx
> Cc: jalemon@xxxxxxxxx; pazy@xxxxxxxxxxxx;
stds-802-17@xxxxxxxx
> Subject: Re: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
>
>
>
> I beg to differ. We had presentations by Sprint at the
working
> group that it is really important where packets get lost.
>
> Losing packet on the media is not acceptable to them.
>
> As I said previously, routers or switches tend to have
> buffers that are orders of magnitude larger than any
> buffer we are considering for the MAC. Therefore,
> loss probability is low at that level and they can
engineer
> their network, (just like they would engineer the media)
> to get the loss statistics where they want them.
>
> cheers,
>
> mike
>
> Italo.Busi@xxxxxxxxxx wrote:
> >
> > See my comment in line
> >
> > Italo
> >
> > > -----Original Message-----
> > > From: pazy@xxxxxxxxxxxx [mailto:pazy@xxxxxxxxxxxx]
> > > Sent: Tuesday, March 19, 2002 3:55 PM
> > > To: jalemon@xxxxxxxxx
> > > Cc: pazy@xxxxxxxxxxxx; stds-802-17@xxxxxxxx
> > > Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
> > >
> > >
> >
> > ...
> >
> > >
> > > Furthermore, if a user traffic is rejected at the
ingress
> point, the
> > > user gets an immediate feedback. Assuming such a
feedback is
> > > useful, how
> > > would a network do it if a given packet was dropped
not
> at the ingress
> > > but rather somewhere on the ring, say on the 5th node
in a
> > > 10-node path.
> > >
> >
> > As far as I know, metro netwoks are tipically made by
many
> > interconnected rings (SBC made a good presentation in
> September about
> > this assumption).
> > This implies that you are loosing packets in the metro
> network so the
> > issue is not completely solved.
> > From the customer point of view there is no difference
> between loosing
> > packets on the ring or in the routers/bridges
interconnecting rings.
> > The big difference is made by the amount of packets
that
> the customer
> > sees as lost at end-to-end perspective ...
> >
> > > Again, I hope that I've managed to clarify my views,
but
> I am not sure
> > > if we "violently agree" or still have some
differences.
> > >
> > > Offer Pazy
> > >
> > > Burlington, MA
> > > Tel: (781)359-9099 x1907
> > >
> > >
> > > -----Original Message-----
> > > From: John Lemon [mailto:jalemon@xxxxxxxxx]
> > > Sent: Monday, March 18, 2002 8:43 PM
> > > To: pazy@xxxxxxxxxxxx
> > > Cc: stds-802-17@xxxxxxxx
> > > Subject: Re: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
> > >
> > > Offer,
> > >
> > > As I mentioned in the Ad Hoc, and as Harry and Yiming
> have reiterated,
> > > there
> > > are trade offs between utilization, delay/jitter, and
> loss. You can
> > > choose
> > > at most 2 of the 3. I believe there is a general
clear
> preference for
> > > lowest
> > > loss most, then for lowest delay/jitter next, and
then for highest
> > > utilization of the available bandwidth last.
> > >
> > > But Yiming's suggestion of allowing this to be
configurable is
> > > intriguing.
> > > While I believe we would always have the order I list
above as the
> > > default,
> > > I could imagine a customer wanting to change it away
from
> the default.
> > > If it
> > > were an option that they didn't have to configure,
those that
> > > wanted to
> > > change from the default would be accommodated; and
those
> that didn't
> > > want to
> > > be bothered with configing yet another parameter
could safely
> > > ignore it.
> > >
> > > John Lemon
> > > ----- Original Message -----
> > > From: "Offer pazy" <pazy@xxxxxxxxxxxx>
> > > To: "'Mike Takefman'" <tak@xxxxxxxxx>; "'Yiming Yao'"
> > > <YYao@xxxxxxxxxxxx>
> > > Cc: <hans-j.reumerman@xxxxxxxxxxx>;
<stds-802-17@xxxxxxxx>
> > > Sent: Monday, March 18, 2002 2:44 PM
> > > Subject: RE: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
> > >
> > >
> > >
> > > I fully concur with Mike's response. We have to be
> extremely careful
> > > about adding optional behavior (and variety) to the
> standard. In my
> > > opinion, we already have far too many options (for
this
> early stage of
> > > the standard development). Options are a nightmare
(and
> if someone can
> > > help me with a stronger word, please do :-) for users
(carriers),
> > > testers, general audience, and finally to ourselves
as we
> will have to
> > > work much harder to make all these options work
together, are
> > > consistent, and that all combinations are covered.
> Additionally, there
> > > is the important issue of interoperability which is
made
> exponentially
> > > more complex with each additional option.
> > >
> > > >From my experience, developers often tend to "be
nice to
> users" by
> > > offering every options possible, just to later be
> rejected by the end
> > > users who don't have the infrastructure, the
personnel, and the
> > > knowledge to sort out the options, to decide, to
manage and
> > > to maintain
> > > their many network nodes.
> > >
> > >
> > > Specifically, please note that the packet loss we are
> considering here
> > > (or considering not allowing) is at the very low
level of
> the physical
> > > level. Look at it as the property of the wire. And at
some
> > > point we must
> > > establish a common model for this "wire" to be able
to
> build the upper
> > > layers. This has nothing to do with the legitimate
topic
> that is being
> > > discussed of policing traffic on the ingress points
to
> the network.
> > > There of course, there are many tradeoffs that are
better
> > > left of to the
> > > operators, and these tradeoffs are much more relevant
to
> > > jitter, latency
> > > and the such.
> > >
> > > Offer Pazy
> > >
> > > Burlington, MA
> > > Tel: (781)359-9099 x1907
> > >
> > >
> > > -----Original Message-----
> > > From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
> > > [mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx] On
Behalf Of
> > > Mike Takefman
> > > Sent: Monday, March 18, 2002 3:37 PM
> > > To: Yiming Yao
> > > Cc: 'hans-j.reumerman@xxxxxxxxxxx';
stds-802-17@xxxxxxxx
> > > Subject: Re: [RPRWG] RAH: Re: Minutes of Rate Ad Hoc
meeting
> > >
> > >
> > > Yiming,
> > >
> > > speaking as a technical expert,
> > >
> > > while I understand your desire to have LP packets
> dropped, be aware
> > > that 802 has never had a MAC that drops packets from
the medium
> > > except due to a CRC errors.
> > >
> > > >From a compliance testing perspective, the issue of
packet drops
> > > would make it difficult (if not impossible) to
provide a test
> > > that proved compliance if packet drops were allowed.
Remember,
> > > if you can't test for compliance, it is not a
standard.
> > >
> > > I believe that proper use of reserved BW will remove
any need to
> > > drop packets. I look forward to seeing the simulation
results
> > > that show problems as a part of the RAH.
> > >
> > >
> > > mike
> > >
> > >
> > > > Yiming Yao wrote:
> > > >
> > > > Hans,
> > > >
> > > > The current draft of the RPR standard tries to
achieve several
> > > objectives: high link utilization,
> > > > guaranteed minimum jitter for reserved HP traffic,
no
> packet loss on
> > > the ring, etc, and these
> > > > objectives are conflicting to each other sometimes.
One
> customer may
> > > want to disallow any LP
> > > > packet drop on the ring even this means high jitter
for the HP
> > > traffic; another may want to
> > > > guarantee minimum jitter to HP traffic (carrying
TDM) at risk of
> > > occasionally dropping some LP
> > > > packets.
> > > >
> > > > My suggestion is that RPR provide a choice for the
> customer to make
> > > his/her decision in conflict
> > > > resolution.
> > > >
> > > > I didn't assume the operator wants to adjust the
total
> > > load/throughput. Maybe this can be done
> > > > more easily if the above choice is provided.
> > > >
> > > > Regards,
> > > >
> > > > Yiming
> > > >
> > > > -----Original Message-----
> > > > From: hans-j.reumerman@xxxxxxxxxxx
> > > [mailto:hans-j.reumerman@xxxxxxxxxxx]
> > > > Sent: Friday, March 15, 2002 1:35 AM
> > > > To: stds-802-17@xxxxxxxx
> > > > Subject: [RPRWG] RAH: Re: Minutes of Rate Ad
Hoc meeting
> > > >
> > > > > Yiming Yao: allow customer to choose between
loss,
> > > jitter, and
> > > utilization
> > > >
> > > > Is the underlying assumption that the operator
of the ring
> > > (=customer?) wants to
> > > > adjust the total load/throughput? Would this
be for
> > > loadbalancing purposes?
> > > >
> > > > regards,
> > > > Hans
> > > >
> > > >
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > Hans-Jürgen Reumerman
> > > > Hans-J.Reumerman@xxxxxxxxxxx
> > > > Digital Communications & networking
> > > pww.pfa.research.philips.com/dc/
> > > > Philips Research Laboratories
> > > Phone: +49 241 6003 629
> > > > Weisshausstr.2, 52066 Aachen, Germany
> Fax: +49 241
> > > 6003 519
> > > >
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >
> > > --
> > > Michael Takefman tak@xxxxxxxxx
> > > Manager of Engineering, Cisco Systems
> > > Chair IEEE 802.17 Stds WG
> > > 2000 Innovation Dr, Ottawa, Canada, K2K 3E8
> > > voice: 613-254-3399 fax: 613-254-4867
> > >
> > >
> > >
> > >
> >
> >
>
--------------------------------------------------------------
> --------------
> ------------------------
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>
> --
> Michael Takefman tak@xxxxxxxxx
> Manager of Engineering, Cisco Systems
> Chair IEEE 802.17 Stds WG
> 2000 Innovation Dr, Ottawa, Canada, K2K 3E8
> voice: 613-254-3399 fax: 613-254-4867
>
>
> _________________________________________________________
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