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

Roy -

I would leave that to the marketing guys ;-)


At 11:52 28/09/2001 -0500, Roy Bynum wrote:
>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 
>>>>>>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