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RE: [EFM] 1 Gbps != 999.9 Mbps (resend)


Ok, so not that you have defined the "system" and all of its functionality, 
what do you call it?

Thank you,
Roy Bynum

At 03:57 PM 9/28/01 +0100, Tony Jeffree wrote:

>Roy -
>The answer to your question, as to how an 802.3 repeater/hub can be part 
>of a manageable system without any 802.1 functionality in that system (by 
>which I assume you mean without a Bridge function in the box), is "very 
>The logical model is of a system that contains an 802.3 hub that has one 
>internal port and N external ports, packaged along with an internal "end 
>station" that does the management (i.e., responds to incoming management 
>requests & returns the appropriate responses), using a conventional SNMP 
>stack, or whatever, for its management communication. This "end station" 
>is attached to the internal hub port via an 802.3 MAC.  Note that, from 
>the hub's point of view (if it can be thought of as having a point of 
>view), the management "end station" looks like any other 802.3 end system 
>that might be attached to its other external ports; in other words, the 
>management "end station" is not part of the hub as such, and plays no part 
>in the functionality of the hub itself, other than as a consequence of the 
>management operations it might be asked to perform.
>At 08:13 28/09/2001 -0500, Roy Bynum wrote:
>>Thank you.  I will remember what you have said.
>>My confusion is how can a "repeater/hub" be a manageable "system" and not 
>>have 802.1 functionality?  Please see the attached product sheet that was 
>>downloaded from a public web site.  Perhaps there needs to be a "little" 
>>more granularity to the terms "hub" and "repeater".  I would argue that 
>>the term "repeater", as a "system", carries with it the connotation that 
>>it does not have any 802.1 functionality and thus can not be managed 
>>through the Ethernet MAC.  I would also argue that a "hub", as a 
>>"system", in order to have management capability, would have 802.1 
>>functionality in order to be managed through the Ethernet MAC.  Perhaps 
>>this is not currently the technically correct usage, but we are about to 
>>get into an area of "systems" definitions for subscription services 
>>support in which the currently technically correct usage is now 
>>inadequate.  In order to preserve the existing "terminology" new terms 
>>need to be agreed on.
>>In the transmission world the term "Customer Service Unit" (CSU) refers 
>>to a "system" that "repeats" the full duplex customer revenue data 
>>stream, while being "managed" though the "out-of-band" overhead by the 
>>service provider.  What ever it is called, EFM needs to standardize on 
>>PHYs that such "systems" could be built from.
>>Thank you,
>>Roy Bynum
>>At 07:07 AM 9/28/01 +0100, Tony Jeffree wrote:
>>>Roy -
>>>I can see where your confusion comes from, if what you do is to use the 
>>>marketing information on products as your basis for an understanding of 
>>>what these terms mean, rather than going to the standards that define 
>>>them and then trying to understand what is in the products.  Let me give 
>>>you an example.
>>>There is a product, manufactured for the SO/HO market by one of the 
>>>usual names in Ethernet equipment, that my local networking supplier 
>>>describes as an "8-port, 10/100 Hub". (Actually, there are a number of 
>>>manufacturers that build similar devices.) Now, we know from Std 802 
>>>that a hub is a multi-port repeater designed for star-wired network 
>>>cabling, so it is a shared medium (half-duplex) device. And we know from 
>>>the 802.3 specs that you cannot mix 10 megs and 100 megs on the same 
>>>shared medium. So what is going on here? On the face of it, this device 
>>>cannot exist, as its spec claims to offer mix-and-match, auto sensing, 
>>>10 or 100 megs on each of its 8 ports.
>>>Look further at the product spec for this device, and it says that the 
>>>hub has Bridge functionality that will do address filtering between 10 
>>>megs ports and 100 megs ports. So what is really going on in this 
>>>particular device is that, logically, it consists of three major components:
>>>- An 8-port 10 megs hub (i.e., a shared medium 8-port 10 megs repeater);
>>>- An 8-port 100 megs hub (i.e., a shared medium 8-port 100 megs 
>>>repeater); and
>>>- A 2-port Bridge connecting the two hubs together (so actually, the 
>>>hubs have 9 ports, with one port on each hub permanently connected to 
>>>the bridge).
>>>So this "box" consists of three separate standardized functions, and 
>>>there is no recognized, standardized name for the combination. The 
>>>nearest match, from the marketing viewpoint, is to call it a hub 
>>>(repeater), as the external ports are all attached to half duplex, 
>>>shared medium LAN segments, and the delivered functionality is therefore 
>>>understandable. However, as it also incorporates a bridging function, it 
>>>is not a hub according to the way that term is defined in 802 - it is 2 
>>>hubs and a bridge that happen to have been packaged in the same box, and 
>>>which happen to be able to share the same set of 8 external RJ45 
>>>connectors. From the manufacturers' point of view, it may well be easier 
>>>to call it a hub than it is to go through a more standards accurate 
>>>description for the benefit of the relatively small percentage of 
>>>customers that would actually understand or care about the difference.
>>>Moral: If you don't want to get confused (or confuse others) in a 
>>>standards forum, or if you simply don't want to remain "just an ignorant 
>>>customer" (your words, not mine!), it is a very smart move to base your 
>>>terminology on the definitions contained in the standards that that 
>>>forum uses/develops, rather than on the marketing information written by 
>>>companies that develop products based on those standards.
>>>At 22:38 27/09/2001 -0500, Roy Bynum wrote:
>>>>I am just an ignorant customer.  When I go to a computer store and buy 
>>>>a "hub", what I get is 802.1d bridge that has half duplex Ethernet 
>>>>ports.  I have an old "hub" that I got from a just such a store.  The 
>>>>box claims 802.1d bridge support.  Perhaps I am guilty of using the 
>>>>vernacular meanings of some terms.  But then, I am just a customer.
>>>>Thank you,
>>>>Roy Bynum
>>>>At 10:51 PM 9/27/01 -0400, Vladimir Senkov wrote:
>>>>>Absolutely agree.
>>>>>I didn't want to repeat myself (here and was trying to do that via 
>>>>>personal e-mails), but i guess I just have to say that those who test they:
>>>>>1) Test equipment vs. technology
>>>>>2) Know what they are testing and what they are expecting as a result
>>>>>Those who sell testing equipment:
>>>>>1) Also sell methodologies, training and certification.
>>>>>2) Some of those methodologies are in the RFCs. There are other 
>>>>>standards for that as well.
>>>>>Those who sell equipment:
>>>>>1) Tell customers exactly what they are selling
>>>>>2) No matter how much they want otherwise, they are going to sell the 
>>>>>EFM, but not the "pure 1G story"
>>>>>EFM needs to address specific needs of those who are going to buy it.
>>>>>Those needs may include: delivering data, video, voice, whatever . . . 
>>>>>to whatever distance, concentration of users, etc. Those needs may 
>>>>>include: security, pricing, etc, etc.
>>>>>but not just "1G". "1G" is not a need. it is more like a sign on a 
>>>>>freeway or something . . .
>>>>>let's say "upto 1G". even with OAM in-band, it will still be "upto 1G".
>>>>>I'll also repeat that Ethernet performance (to the end user anyway) is 
>>>>>NOT measured in bits per second. And nobody is selling 10Mbps 
>>>>>repeaters/hubs (yes hub IS a repeater :) for example. They sell 
>>>>>Ethernet hubs instead.
>>>>>Therefore, customer who buys such a hub knows that he is not going to 
>>>>>sue the seller for not delivering 10Mbps. Customer will only expect 
>>>>>performance characteristics of that device to be tested against 
>>>>>Ethernet performance measurement methodologies.
>>>>>-----Original Message-----
>>>>>From: Andrew Smith 
>>>>>Sent: Thursday, September 27, 2001 10:21 PM
>>>>>To: Roy Bynum
>>>>>Cc: 'stds-802-3-efm'
>>>>>Subject: RE: [EFM] 1 Gbps != 999.9 Mbps
>>>>>I'd be interested to see how you propose measuring one of your
>>>>>802.3x-pause-rate-limited services against one of these "certification"
>>>>>testers. But seriously, folks, to paraphrase that doctor-patient story
>>>>>"Patient: Doctor, it hurts when I sell my customers 1000000000.0000 bps
>>>>>service. Doctor: then don't sell them that, sell them what you can
>>>>>Andrew Smith
>>>>>-----Original Message-----
>>>>>Behalf Of Roy Bynum
>>>>>Sent: Thursday, September 27, 2001 4:36 PM
>>>>>To: bob.barrett@xxxxxxxxxxxxxxx; Harry Hvostov; fmenard@xxxxxxxxxxxxxxx;
>>>>>'Denton Gentry'
>>>>>Cc: 'stds-802-3-efm'
>>>>>Subject: RE: [EFM] 1 Gbps != 999.9 Mbps
>>>>>You would be surprised at how little bandwidth loss it takes for equipment
>>>>>to fail certification in a services infrastructure deployment approval
>>>>>process.  If we tell our customers that we are delivering a GbE, then we
>>>>>deliver a GbE that will pass their most rigorous performance test,
>>>>>including throughput.
>>>>>Thank you,
>>>>>Roy Bynum
>>>>>At 12:11 AM 9/28/01 +0100, Bob Barrett wrote:
>>>>> >Harry et al
>>>>> >
>>>>> >yup, all the IP 'stuff' is payload as far as the demarcation point is
>>>>> >concerned.
>>>>> >
>>>>> >The demarc is a PHY that carries packets at the end of the day. Some
>>>>> >may be buried inside a bigger system, however, the standard must 
>>>>> also cater
>>>>> >for stand alone demarc devices. My expectation as a user would be 
>>>>> that at
>>>>> >the demarc the bandwidth was the same capacity as my enterprise MAC 
>>>>> and PHY
>>>>> >of the same spec.
>>>>> >
>>>>> >Would I miss 10k per second on a 1GE, I doubt it.
>>>>> >
>>>>> >Would my test gear pick it up on an end to end private circuit test, I
>>>>> >know, anyone on the reflector tried this?
>>>>> >
>>>>> >Bob
>>>>> >
>>>>> > > -----Original Message-----
>>>>> > > From: Harry Hvostov 
>>>>> [<mailto:HHvostov@xxxxxxxxxxxx>mailto:HHvostov@xxxxxxxxxxxx]
>>>>> > > Sent: 27 September 2001 17:41
>>>>> > > To: 'fmenard@xxxxxxxxxxxxxxx'; 'Denton Gentry';
>>>>> > > bob.barrett@xxxxxxxxxxxxxxx
>>>>> > > Cc: 'stds-802-3-efm'
>>>>> > > Subject: RE: [EFM] 1 Gbps != 999.9 Mbps
>>>>> > >
>>>>> > >
>>>>> > > And how about the ICMP and IGMP traffic from the same CPE devices?
>>>>> > >
>>>>> > > Harry
>>>>> > >
>>>>> > > -----Original Message-----
>>>>> > > From: Francois Menard 
>>>>> [<mailto:fmenard@xxxxxxxxxxxxxxx>mailto:fmenard@xxxxxxxxxxxxxxx]
>>>>> > > Sent: Thursday, September 27, 2001 6:05 AM
>>>>> > > To: 'Denton Gentry'; bob.barrett@xxxxxxxxxxxxxxx
>>>>> > > Cc: 'stds-802-3-efm'
>>>>> > > Subject: RE: [EFM] 1 Gbps != 999.9 Mbps
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > > Or for that matter, what about ARP traffic unsolicited from my CPE
>>>>> > > devices ?
>>>>> > >
>>>>> > > -=Francois=-
>>>>> > >
>>>>> > > -----Original Message-----
>>>>> > > From:
>>>>> > > 
>>>>> [<>] 
>>>>> On Behalf Of Denton
>>>>> > > Gentry
>>>>> > > Sent: September 26, 2001 3:12 PM
>>>>> > > To: bob.barrett@xxxxxxxxxxxxxxx
>>>>> > > Cc: stds-802-3-efm
>>>>> > > Subject: [EFM] 1 Gbps != 999.9 Mbps
>>>>> > >
>>>>> > >
>>>>> > >
>>>>> > > > Service providers have a desire to offer a full 1GE service and not
>>>>> > > > use any of it's bandwidth for OAM. The rule of conservation of
>>>>> > > > bandwidth means the OAM needs to go somewhere other then in the
>>>>> > > > bandwidth reserved for the 1GE payload. I take it as read that 100%
>>>>> > > > utilisation of a 1GE is unlikely, but that is not the point. 
>>>>> The point
>>>>> > >
>>>>> > > > is that service providers want to offer 1GE service period, not a
>>>>> > > > 999.9Mbit service.
>>>>> > >
>>>>> > >   Does the existence of the Mac Control PAUSE frame therefore make
>>>>> > > Ethernet unsuitable for service providers?
>>>>> > >
>>>>> > > Denton Gentry
>>>>> > > Dominet Systems