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[802.3ae] Re: M0 Line remote error indiation support for WIS


I believe the WIS does not need to support the M0 Line-REI byte
(per ITU-T G.707 Rev 2000) for the following reasons:

1- Even with BER of 1E-6, which is quite high, one should only
observe an average of 9835 Line BIP errors per second (this is
the default Line SES threshold adopted by the WIS MIB). This
corresponds to an average of less than two Line BIP errors per frame.
Therefore, a single byte REI-L (i.e., M1 only, which can report up
to 255 BIP errors per frame) seems to be enough.

2- The WAN PHY as defined today will be compatible with old and new
equipment since, as you stated below, as per ITU-T G.707 Revision 2000
new equipment should support both modes of operation.

Norival Figueira
Nortel Networks

At 12:33 PM 9/5/01 -0700, Kumar, Pankaj wrote:
Hello all,
WAN interface sub-layer support only M1 byte for STS-N line remote error
indication as described in the structure of section and line overhead
generated by WIS in figure 50-8 of P802.3ae_D3_2.cb

ITU-T G.707 Revision 2000 has added M0 Line-REI byte in addition to M1 for
STM-64 (10G) frames and above ( 40G) . The M0 byte will be located right
before the M1 byte. The M0 and M1 bytes convey the count of interleaved bit
blocks that has been detected in the error by the BIP-1536 (in the range of
[0, 1536]). M0 bit 1 is most significant bit and M1 bit 8 is least
significant bit. If interworking with old equipment supporting the single
byte REI in M1, the value conveyed is truncated at 255 and inserted in M1.

For backward compatibility, ITU-T specifies that for 10G frames, new
equipment (10/2000 onward) should be able to support both modes : one-byte
L-REI (M1) with a truncated value, as well as 2-byte L-REI (M0M1) with
non-truncated REI.

Since 10 Gbit/s WIS is defined after October 2000 and WAN-PHY would
interface to SONET/SDH infrastructure. So WIS should also support the M0
with backward compatibility. The interworking should be configured by the
management system.

What you all think about the M0 support in WIS .

Pankaj Kumar
Optical Products Group
Intel corporation
201 Mission St. 5th Floor
San Francisco, Ca, 94105
(415)  536-2166
pankaj.kumar@xxxxxxxxx <mailto:pankaj.kumar@xxxxxxxxx