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


Dave, Pankaj,

Thanks for your information.  Yes, that is exactly what I wanted 
to know.  I think that these alarming reactions in WIS should also 
be documented in 802.3ae.


I asked the question since I was not sure whether ELTE on the 
Ethernet side is lit on or not when its SONET side receives 
such AIS signals.  Shutting down the light is the simplest 
way to notify the remote fault to WIS, but it prevents WIS 
from localizing the fault location.

Here I see the similar issue in 40km+ LAN-PHY Link, especially 
when implemented with optional XAUI interface.  

Let me assume that the far-end (remote) PHY is implemented as 
an independent PHY package connected with a MAC/router package 
via backboard XAUI interface.  

Then what happens if the MAC/router package is shutting down or 
broken down?  Should the PHY package be shutting down at the 
same time? Or can we design the PHY package to be kept lit on 
and just sending the AIS (Alarm Indication Signal) without 
breaking the Layer-1 connection?

From the view point of fiber plant management, I hope that the 
latter implementation, the PHY package beeing kept lit on 
regardless of its valid XAUI connection or not, would be allowed 
in the 802.3ae standard.  This helps us to localize the fault 
location; Layer-1 link or far-end MAC.  Also Layer-1 link 
performance can be monitored continuously if it is required 
for our SLA.

However, I am not sure that this implementation is allowable 
or not in 802.3 tradition/standardization.  If you see some 
issues in this type of implementation, please let me know the 

Best Regards,

At 09:34 00/06/09 -0700, Pankaj Kumar wrote:
>     In the WAN PHY, Beside the  line AIS  ( With K2 byte processing ) 
> and path AIS ( Pointer bytes processing ), Other SONET/SDH higher 
> layer ( Section, Line ) alarms like Loss of signal ( LOS), Loss of 
> Sonet/SDH frame etc should  Disable the 66/64 Decoder and the Loss 
> of Delineation defect should be detected , Then MAC will discard 
> frame. 

At 09:57 00/06/09 -0400, David Martin wrote:
> Your description is correct. If you're asking how the WAN PHY 
> will react to Line/Path AIS, the pointer processor will detect 
> AIS-P and the all ones signal will be passed from the WIS up to 
> the 66/64 decoder, which will lose sync (e.g. LOD defect, Loss 
> Of Delineation), then the MAC will see the ReceiveDataValid 
> line inactive & discard frames.  

At 19:24 00/06/09 +0900, Osamu ISHIDA wrote:
> Could you help me to understand how WAN-PHY and ELTE would react on 
> SONET AIS (Alarm Indicaton Signal)?
> When we have cable cut in SONET infrastructure, the SONET side of 
> the ELTE will receive either Line-AIS or Path-AIS.
>   Line-AIS: all '1' in Line OH and SPE payload.
>             generated by the regenerator who detect upstream cable cut.
>             detected by the last 3 bits in K2 (at least 3 consecutive '111')
>   Path-AIS: all '1' in AU pointer and SPE payload.
>             generated by LTE who detect upstream cable cut.
>             detected by the all '1' in H1&H2 at least 3 consecutive frames.
> Thank you,
> Osamu

Osamu Ishida,ishida@xxxxxxxxxxxxxxxxxxx
NTT Network Innovation Laboratories
TEL:+81-468-59-3263 FAX:+81-468-55-1282