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RE: Clock Tolerance and WAN PHY


Yes there are some "service providers" that are attempting to use GbE for a 
VLAN type of VPNs for Internet types of services.  They are restricted to 
local metro systems, even with the extended distance PHYs.  I have talked 
with some engineers that support those networks.  The labor overhead for 
fault and performance management at remote sites is very expensive.  They 
are looking forward to an Ethernet PHY that includes operations management 
functionality like the WAN PHY.    In the mean time, they are making do 
with what they have just to create market share.  Please do not confuse 
what WAN networking people have had to do for years, make do with what they 
had because they could not get what they really wanted or needed.  As a 
customer, a data network architect, an implementor of LAN and WAN networks, 
and someone who has had to support LAN and WAN networks, I am making a 
statement for what is needed and wanted in order to do WAN optical 
networking, the WAN PHY with operational maintenance functionality.

Thank you.
Roy Bynum

At 03:23 PM 1/29/01 -0800, Tricci So wrote:
>Pat, many thanks to you for the info.  What you said makes more sense to me.
>This also implies to me that it is feasible today to have 10GigE runs over
>optical without SONET.  It is also my understanding that there are some
>tier-1 service providers using GigE interface as a simple LAN transport
>within the big POP to interconnect their regional routers together.  For
>this type of scenario, there is no existing SONET infrastructure, and
>therefore, there is no need for WAN PHY.  What they are looking for is just
>a reliable, cost efficient, high capacity transport.
>-----Original Message-----
>From: pat_thaler@xxxxxxxxxxx [mailto:pat_thaler@xxxxxxxxxxx]
>Sent: Monday, January 29, 2001 1:04 PM
>To: rabynum@xxxxxxxxxxxxxx; rtaborek@xxxxxxxxxxxxx;
>Subject: RE: Clock Tolerance and WAN PHY
>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.
>-----Original Message-----
>From: Roy Bynum [mailto:rabynum@xxxxxxxxxxxxxx]
>Sent: Monday, January 29, 2001 5:06 AM
>To: rtaborek@xxxxxxxxxxxxx; HSSG
>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>