Re: PMD discussion
Stuart,
I never said that that locating the WIS at the end of a LAN PHY was the ONLY way
to connect 10 GbE to SONET. In fact, I used the word ALTERNATIVE in my
illustration. I believe its very important to point out all the alternatives in
a standards process, it helps us meet the PAR's 5 criteria.
I'm just pointing out that the WAN PHY is not the ONLY way to provide SONET
compatibility. Alternatively, SONET compatibility can be achieved with the
simple and inexpensive LAN PHY and a WIS element used whenever it is needed.
It's the WIS that provides Ethernet-to-SONET layer 1 bridging, not the WAN PHY.
I'm all for standardizing the WIS and leaving implementations, including the WAN
PHY, out of the picture.
That said. I'll turn your argument right around on you. It makes more sense that
way:
Currently, ALL Ethernet links that go into the WAN, or SONET do not employ a WAN
PHY. Ethernet links to SONET are generally SONET, typically carrying
Packet-Over-SONET traffic. These links are typically much more expensive that
their Ethernet counterparts. This leads to a strong desire to cost reduce the
links.
The WAN PHY proposal supports 10 GbE LAN connectivity to SONET, but by requiring
SONET-like (sorry, but a WAN PHY bears little if any resemblance to Ethernet).
Doesn't the WAN PHY sound like a specific implementation to solve a simple
problem.
BTW, I'm having a difficult time with your argument with respect to the 1550 nm
PMD. I view 1550 nm in much the same way as the WAN PHY, a non optimal solution
for SONET compatibility.
Let's also not confuse the issue. The WAN PHY is not intended for use over the
SONET infrastructure. That's SONET's domain.
I heartily agree with your last statement: "There may be options to where the
WIS could be placed. However, the standard should not be such that it dictates
where."
Are we perhaps in agreement?
Best Regards,
Rich
--
Stuart Robinson wrote:
>
> Hi Rich,
>
> I think that the confusion comes from the discussion of the standard versus
> one possible implementation. It seems like you are trying to have one
> implementation as the standard.
>
> If I follow your arguement, then Serial 1550nm optics may meet the distance
> objectives in the same way your LAN PHY + WIS may meet the WAN PHY
> objectives. However, these are not necessarily optimized for their
> respective applications.
>
> Your LAN PHY + WIS (with the WIS being in the transport equipment) is
> putting a long interface (ie SERIAL LAN PHY) between the PCS and WIS (stack
> diagram on Pg 4 of
> http://grouper.ieee.org/groups/802/3/ae/public/may00/bottorff_1_0500.pdf).
>
> One may argue that this meets the objectives but it is not necessarily
> optimized for applications that run over SONET infrastructure or "Optical
> Network" equipment (which are actually based on SONET).
>
> There may be options to where the WIS could be placed. However, the
> standard should not be such that it dictates where. Vendors may achieve
> Howard's Nirvana - LAN PHY, WIS, and SERDES in one device (p16 of
> frazier_1_0300.pdf link enclosed below).
>
> Regards,
>
> Stuart
>
> -----Original Message-----
> From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxx]
> Sent: Monday, May 29, 2000 2:27 PM
> To: HSSG
> Subject: Re: PMD discussion
>
> Jay,
>
> I agree with you. However, I believe that we are loosing sight of the
> ultimate
> goal of the WAN PHY: Compatibility with the SONET/SDH infrastructure.
>
> I'd like to address a comment regarding our objectives that was made during
> the
> Ottawa meeting on several occasions: It was said that a LAN PHY with a WIS
> (for
> SONET/SDH compatibility) does not meet the HSSG objectives. I'm having
> trouble
> understanding why a solution which "exceeds" the objectives, and is highly
> likely to be lower in cost, is inferior to one which "meets" the objectives.
>
> The specific objective in question is as follows:
>
> Define two families of PHYs
> - A LAN PHY, operating at a data rate of 10.000 Gb/s
> - A WAN PHY, operating at a data rate compatible with the payload rate of
> OC-192c/SDH VC-4-64c
>
> It has been proposed, and there is general agreement (i.e. lack of any other
> proposal) that the WIS, a layer 1 (PHY) sublayer is used to encapsulate
> Ethernet
> packets, using 64B/66B for a PCS, for transport over SONET/SDH. The latest
> relevant proposals from Ottawa are:
>
> http://grouper.ieee.org/groups/802/3/ae/public/may00/bottorff_1_0500.pdf
> http://grouper.ieee.org/groups/802/3/ae/public/may00/nicholl_1_0500.pdf
> http://grouper.ieee.org/groups/802/3/ae/public/may00/walker_1_0500.pdf
>
> The location of the WIS in a WAN PHY can be illustrated as follows:
>
> +-----+ +-----+ +-----+ +-----+
> --->| |--->| PHY |------->| |--->|SONET|
> | MAC | | | medium | PHY | | \ |
> <---| |<---|(WIS)|<-------| |<---| SDH |
> +-----+ +-----+ +-----+ +-----+
> (rate
> controlled) |<--- WAN PHY ---->|
>
> Alternatively, the location of the WIS in a LAN PHY can be illustrated as
> follows:
>
> +-----+ +-----+ +-----+ +-----+
> --->| |--->| |------->| PHY |--->|SONET|
> | MAC | | PHY | medium | | | \ |
> <---| |<---| |<-------|(WIS)|<---| SDH |
> +-----+ +-----+ +-----+ +-----+
> (rate
> controlled) |<--- LAN PHY ---->|
>
> Note that the WIS function simply moves to the right (towards SONET/SDH) and
> the
> same PHY, a LAN "UniPHY" if you will, may be used to achieve full SONET
> compatibility. MAC/PHY rate control is not issue between the two methods. I
> understand how to implement it either way.
>
> Please point out the flaw(s) with the LAN UniPHY in supporting Ethernet over
> SONET. Is it that there is a unwritten requirement for a WAN PHY to support
> payloads other than Ethernet over SONET/SDH? I'd call any such requirements
> out
> of the scope of IEEE 802.3.
>
> Best Regards,
> Rich
>
> --
>
> jay.hoge@xxxxxxxxxxxxxx wrote:
> >
> > In order for the WAN PHY to do its job, it cann't use a line code or else
> > the data rate will exceed that of OC-192. Scrambling anyone?
> >
> > Jay
>
> -------------------------------------------------------
> Richard Taborek Sr. Phone: 408-845-6102
> Chief Technology Officer Cell: 408-832-395
> nSerial Corporation Fax: 408-845-6114
> 2500-5 Augustine Dr. mailto:rtaborek@xxxxxxxxxxx
> Santa Clara, CA 95054 http://www.nSerial.com
>
> --------------------------------------------------------------------------------
>
> frazier_1_0300.pdf.urlName: frazier_1_0300.pdf.url
> Type: Internet Shortcut (application/x-unknown-content-type-InternetShortcut)
-------------------------------------------------------
Richard Taborek Sr. Phone: 408-845-6102
Chief Technology Officer Cell: 408-832-3957
nSerial Corporation Fax: 408-845-6114
2500-5 Augustine Dr. mailto:rtaborek@xxxxxxxxxxx
Santa Clara, CA 95054 http://www.nSerial.com