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

Re: [802.3BA] 40G/100G SMF distinct identity [WAS: RE: [802.3BA] 5 Criteria mod to support 40 G on SMF]


You said:

Being a data communications guy, I don't understand why FC seems to be
increasing by factor 2 each generation, instead of factor 4 or 10. 
Representatives for Brocade (in my mind primarily FC vendor) says
customers want small increases in link speed, which is not my

I'm the Brocade representative, so I'll attempt to answer the question
regarding why FC continues to grow by factors of 2 instead of 4 or 10.
I never said customers want small increases in link speed, but I'll say
that they want it if its no additional cost or even a reduction in cost.

Fibre Channel has always attempted to be the low cost leader in fiber
optic bandwidth. Fibre Channel standardized the first 1 gigabit links
based on VCSELs that were very successful.  Ethernet saw the advantage
of this and soon copied large parts of the specification and developed
highly successful 1 Gig fiber optic links using the same technologies.
Most 1 Gig FC and 1 Gig Ethernet fiber optic transceivers work on either

Many small improvements in transceivers lead to big differences.  Fibre
Channel saw that they could soon advance to 2 Gig and be backward
compatible with 1 gig for basically no additional cost or even less cost
when new processes were developed.   Customers liked doubling the speed
for no additional cost and it still autonegotiated down to 1 Gig if
needed. The same shift was seen for 4 Gig when almost all 2 Gig gear was
obsoleted by the new gear.  The speed doubling usually coincided with
new ASIC development and gained other capabilities with the speed
increase. Speed sells and there were no interoperability problems
between the speeds.

You see much smaller speed jumps in microprocessor speeds and disk drive
capacities.  Does anyone complain when a processor increases from 2.1
GHz to 2.4 GHz as long as it works?

Fibre Channel is currently going through the transition to 8 Gig and
there is currently a cost premium over 4 Gig solutions, so the
transition to 8 Gig might not be as fast as from 1GFC to 2GFC or 2GFC to
4GFC, but the cost difference is diminishing and customers are adopting
8GFC rapidly in the first quarter of released products.

Fibre Channel did make the mistake of following Ethernet into the 10 Gig
space.  10GFC has seen minimal adoption because of the high cost premium
over even 8GFC. No servers have adopted 10GFC and FC HBAs are not
expected to move to 10GFC but to 8GFC and then 16GFC.  Ethernet has seen
a very similar lack of adoption of 10 Gig because it isn't backward
compatible with 1GE.  GigE has been very successful because of its
backward compatibility with 10/100.  In 2007, over 1 million 10GE ports
were shipped compared to over 100M Gig E ports.  Six years after the 10
Gig standard was complete, less than 1% of Ethernet ports are 10 Gig.

I was at OFC this week and the high cost of 10 Gig was a big topic of
debate. We're still in a chicken and egg scenario with 10 Gig.  Volumes
could drive the cost of 10 Gig down, but we haven't seen it yet.  Users
would like 10 Gig on servers, but mainly buy 1 Gig.  I've heard that
only about 100,000 servers connected with 10GE last year.

I've tried to make the point that users don't mind minimal speed
increases for minimal or no cost increases as long as they are backward
compatible.  Fibre Channel is attempting to continue that tradition with
8GFC and 16GFC.  Just in time technologies that have been optimized
instead of before there time technologies that are not cost-effective.

My 10 cents,
Scott Kipp 

-----Original Message-----
From: Mikael Abrahamsson [mailto:swmike@SWM.PP.SE] 
Sent: Saturday, February 16, 2008 12:35 PM
Subject: Re: [802.3BA] 40G/100G SMF distinct identity [WAS: RE:
[802.3BA] 5 Criteria mod to support 40 G on SMF]

On Sat, 16 Feb 2008, Alessandro Barbieri (abarbier) wrote:

> This group has identified a minimum set of applications that is 
> sufficient to justify the DI of 40G and 100G, that should be enough. 
> We can't pretend 40G will not find its way into the aggregation. Much 
> like in 10-12 years 100G will find its way into the server market.

Sorry for my previous email where I used "price" instead of "cost". I'll
try to improve.

So, backing up a bit, I'm trying to see this from a system perspective,
ie in the equipment where these technologies are going to be used.

I have some thinking I would like some vendors to give feedback on,
which I think is important in this decision as well.

Currently, a lot of the current highend platforms use 40 gigabit/s
backplane connectivity. Would they get 40GE support on the current
chassis/fabric generation in 2010?

By 2010, my guess is that highend platforms will have backplane
connectivity somewhere in the 100, 120, 160 or 200 gigabit/s speeds.

If 100, this would enable single port 100GE or two port 40GE blades.
If 120, this would enable single port 100GE or three port 40GE blades.
If 160, this would enable single port 100GE or four port 40GE blades.
If 200, this would enable dual port 100GE or five port 40GE blades.

Would the 40GE blades have pluggable optics that would support all
proposed reaches? If there is a push for 10km SMF reach for 40GE, why
not 40 or 80km reach there as well? With 3 or 4 port 40GE blades one
would have capacity to on a single blade create rings and then use 40GE
as aggregation technology immediately. Then it makes sense to have 10
and 40km SMF reaches (and seeing that 10GBASE-ZR is actually used quite
a bit, wouldn't 80km as well be of interest to standardize by the same
logic that vendors will standardize 40GE-10km SMF if IEEE doesn't)?

I also think that any proponent for 40GE needs to explain what the next
step after 100GE should be, as 40GE creates a precedent for 250GE or
400GE as next step if the logic is to be intact.

Being a data communications guy, I don't understand why FC seems to be
increasing by factor 2 each generation, instead of factor 4 or 10. 
Representatives for Brocade (in my mind primarily FC vendor) says
customers want small increases in link speed, which is not my
In the ISP world people often want to use their equipment for a long
time and write them off in 3-6 years, as they are usually quite big and
big in capital spending, thus the need for factor 4 or 10 in speed
increase over the previous generation.

I also feel that 40GE was pushed as server technology needed in 2012, in
order to make 40GE worthwile it needs to be here before 100GE, not
after, or show big cost savings so as to be more economical per bit
compared to 100GE. Being compatible with existing equipment (new
linecard for existing
platforms) might cause it to be more economical for end users from a
total expenditure perspective.

Being an ISP guy, I also feel that any push for 40GE needs to have broad
switch/router vendor support, because if the core routing platforms
doesn't support 40GE then there is a big hurdle in how to connect the
aggregation to the core for any larger sized ISP who has a WAN.

But then again, if 40GE 10km SMF uses a lot of 10GE technology and has a
2.5x cost increase over 10GE, and 100GE has 10x cost increase, and 40GE
can be brought quickly to market and 100GE will take more r&d and is
harder to realise, then 40GE SMF might still have a place.

But I do have to say again: 40GE cannot delay 100GE effort, it's needed
soon of not NOW. 40GE is bandaid for ISPs, the solution is 100GE if not
higher speeds, or we risk stalling the growth of the Internet.

Mikael Abrahamsson    email: