Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

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


Now we have a problem.  What to call it as part of our discussions.  If you 
leave it up to the marketing guys then you have just validated everything 
that I have been saying, even if it is technically incorrect per the 802.3 
standard.  You can't have it both ways.

Thank you,
Roy Bynum

At 06:23 PM 9/28/01 +0100, Tony Jeffree wrote:

>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 easily".
>>>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 
>>>>>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