Subject: RE: draft-nadeau-pwe3-oam-msg-map-04.txt

From: "Busschbach, Peter B (Peter)" <[email-masked]>
Date: Wed, 24 Mar 2004 10:00:41 -0500

Ben,

If you read the draft, you will see that at no point it is suggested that ATM or SONET alarms should be mapped to PW alarms. However, there are protocols that don't have the same in-band OAM mechanisms as ATM and SONET, viz Frame Relay and Ethernet. In Frame Relay, the way an alarm at one NNI is conveyed to another NNI is not specified in the standards. When a PW is used to connect the two NNIs, it was decided to use PW Status messages to convey alarms. This is what the draft describes and this is why the introduction mentions "vice versa".

Peter

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]
> Sent: Wednesday, March 24, 2004 9:23 AM
> To: [email-masked]
> Subject: RE: [PWE3] draft-nadeau-pwe3-oam-msg-map-04.txt
> 
> 
> Folks,
> 
> draft-nadeau-pwe3-oam-msg-map-04 states in the introduction 
> "This document describes ... how faults detected in 
> pseudo-wires are mapped to OAM messages native to the 
> emulated services and vice versa".
> 
> I can see the need to map OAM up the network stack from the 
> server layer OAM (e.g. a MPLS server layer) to the client AC 
> OAM (e.g. an ATM client layer) but why is there a need to map 
> OAM down the network stack from AC OAM to server layer OAM?
> 
> For example, today there are client/server relationships 
> where ATM VPs (the client) are transported over SDH VC_4s 
> (the server), defects in the SDH server layer are mapped 
> upwards to the ATM client layer.  However defects in the ATM 
> client layer are not mapped down to the SDH server layer.  
> This is because defects in the client layer do not affect the 
> server layer whereas defects in the server layer do affect 
> the client layer.
> 
> Thanks
> Ben
> 
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