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RE: [EFM] 1 Gbps != 999.9 Mbps


999.9 Mbps is within 100 ppm of 1 Gbps.  Does the delivered bit rate need to
be more precise than that?  Suppose the OAM overhead is lower, such as the
10K mentioned below, is that still too much?

It seems to me that, if the requirement is to provide customers with the
type of isochronous-type of service they can get from T1, DS[x], or ATM-type
interfaces, with bit throughput guaranteed and drived from some precision
clock hierarchy, then perhaps Ethernet is not the best choice to meet this

Ethernet instead has tended to talk about "Classes" of networks that
reference the raw bitrate, but don't really guarantee precise throughput,

I would think that if a service was being sold as providing "1000BASE-x
performance", most customers would comprehend what that was like. And
certainly perceive it as a very attractive offering.  Perhaps provisions
could be made in the EFM specs. to add isochronous-type guarantees, but one
needs to ask whether doing so would compromise the simplicity and
flexibility that makes Ethernet so attractive for EFM in the first place.
I'm just worried about the dangers of "feature creep".

Barry O'Mahony
Intel Architecture Labs
Hillsboro, OR, USA
tel: +1(503)264-8579

-----Original Message-----
From: Bob Barrett [mailto:bob.barrett@xxxxxxxxxxxxxxx]
Sent: Thursday, September 27, 2001 4:11 PM
To: Harry Hvostov; fmenard@xxxxxxxxxxxxxxx; 'Denton Gentry'
Cc: 'stds-802-3-efm'
Subject: RE: [EFM] 1 Gbps != 999.9 Mbps

Harry et al

yup, all the IP 'stuff' is payload as far as the demarcation point is

The demarc is a PHY that carries packets at the end of the day. Some demarcs
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 don't
know, anyone on the reflector tried this?


> -----Original Message-----
> From: Harry Hvostov [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]
> 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