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Re: Clock Tolerance and WAN PHY


Fibre Channel, contrary to what the minority may say, is a SAN
technology. The "S" stands for Storage. FC usage for LAN, MAN and WAN
applications is minimal at best. SAN technology applications generally
focus on high performance storage access. Prior to Fibre Channel, these
applications were served by IBM's ESCON and equivalent proprietary
technologies on the high end and SCSI on the low end (of servers).

Ethernet, contrary to what the minority may say, is a LAN technology.
The "L" stands for Local. Ethernet usage for SAN, MAN and WAN
applications is minimal at best. Ethernet has essentially no challenge
in the LAN and is slowly expanding into the MAN and WAN. I agree with
Pat's statements with respect to Ethernet's relative performance to
Fibre Channel in support of SAN applications, it is currently inferior.

What's left out in the cold is SONET, ATM, the WAN PHY, etc. These
protocols will likely NEVER be supported by servers to any appreciable
extent. Therefore, protocol conversion must occur in order to transport
LAN and SAN information over the existing MAN and WAN infrastructure.
The way things are going to change seems pretty obvious to me.

What role does the 10GE LAN PHY play you ask? A HUGE ONE!!!

Best Regards,

Roy Bynum wrote:
> Pat,
>  From what you are telling me, only if 10GbE replaces FC will there be a
> major computer/server market for the 10GbE LAN PHY?
> I personally would like to see a single ubiquitous data link protocol for
> all data services.  Before that happens however, FC will need to obsoleted
> the way that Token Ring was.  Because P802.3ae has supported the
> development of the next generation of FC through XAUI, that will not happen
> anytime soon.  The development of XAUI and the four lambda PHY which will
> be used by FC, the market for the 10GbE LAN PHY was greatly reduced.
> Since high bandwidth FC continues to be a major player in the
> computer/server market, what role does 10GbE LAN PHY play?
> Thank you,
> Roy Bynum
> At 02:03 PM 1/29/01 -0700, pat_thaler@xxxxxxxxxxx wrote:
> >Roy,
> >
> >It would make our jobs easier (though less profitable) if we could plan for
> >next year's network development based on what computer systems do today.
> >Technology continues to evolve and there are some developments in progress
> >that will impact system bandwidth needs.
> >
> >Today most large systems access their storage through Fibre Channel links
> >and access the rest of the world through Ethernet links. The Ethernet NICs
> >leave all or most of the TCP/IP handling to software which has to touch
> >every packet. Therefore, pushing a Gigabit data rate takes a lot of CPU
> >cycles.  The Fibre Channel links do a lot of the packet processing in
> >hardware. In an unerrored transfer case, the software above a Fibre Channel
> >card gets messages built from many packets. They get up to Gigabit data rate
> >with much less system load.
> >
> >People are developing iSCSI and iFCP protocols to support storage traffic
> >over Ethernet. In conjunction with that, there is also development of
> >hardware that will provide hardware functionality for these protocols
> >similar to that achieved by Fibre Channel. An Ethernet adapter may then be
> >used to support  Ethernet traffic plus storage traffic with system
> >efficiency about that of FC.
> >
> >This development can increase the data rate needs/capability of servers up
> >to the point where they need 10 Gbit.
> >
> >Regards,
> >Pat
> >
> >-----Original Message-----
> >From: Roy Bynum [mailto:rabynum@xxxxxxxxxxxxxx]
> >Sent: Monday, January 29, 2001 5:06 AM
> >To: rtaborek@xxxxxxxxxxxxx; HSSG
> >
> >Rich,
> >
> >I am not sure if anyone has done in technical or economic study of how many
> >servers within the next two years will be able push close  to 10Gb of data
> >into a LAN PHY.  From what I have been told, computer systems today can not
> >even push enough to fill a GbE link, much less a 10GbE link.  Without a
> >computer/server market, the 10GbE LAN PHY will be relegated to bandwidth
> >aggregation within privately owned campus fiber plant or a large data
> >room.  The 10GbE WAN PHY, is easily used extended LANs over leased fiber;
> >MANs over privately owned or leased fiber and wavelengths; WANs over DWDM
> >wave lengths or leased fiber.
> >
> >Given the amount of GbE that is being used by "legacy-free carriers" in the
> >U.S.A. and Europe, and the expansion of the Internet, the need for a
> >"service provider" type of Ethernet is becoming a major market
> >issue.  Combined with the other uses of the 10GE WAN PHY, I believe that a
> >very high percentage (75%?) of 10GbE will be implemented using the WAN
> >PHY.  The WAN PHY will be used because it has the operational management
> >functionality required.  If P802.3ae does not go ahead and put the
> >operational management functionality that is being recommended, all of the
> >vendors will be implementing "proprietary" versions that will have it.  If
> >P802.3ae does not do it, then the need to do it in proprietary
> >implementations will give 802.3 a "major black eye".
> >
> >I tend to agree with Gary Nicholl in the need for a + 20 PPM
> >clock.  Perhaps someone could give a relative cost to implement a + 20 PPM
> >clock instead of a + 100 PPM clock.
> >
> >Thank you,
> >Roy Bynum
> >
> >     <Previous emails in the string deleted>
Richard Taborek Sr.                 Phone: 408-845-6102       
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