Subject: Re: [OPSAWG] Last Call: <draft-ietf-opsawg-oam-overview-08.txt> (An Overview of Operations, Administration, and Maintenance (OAM) Mechanisms) to Informational RFC

From: Thomas Narten <[email-masked]>
Date: Tue, 12 Feb 2013 12:38:32 -0500

I agree with many of the comments that others have raised on this
thread. Just a couple of things to add that I don't recall seeing
mentioned.

   An OAM protocol is run in the context of a Maintenance Domain,
   consisting of two or more nodes that run the OAM protocol, referred
   to as Maintenance Points (MP).

This defintion could be better. I assume an MD is really more like a
"region", that is a collection of nodes within which (or across which)
some OAM function is run. You might run, e.g., a ping. While that ping
may be between to MPs, it also involves other nodes (MIs). But MIs seem
to be excluded per the above.

   o Continuity Checking (CC):
      Used for verifying the liveness of a connection between two MPs.

What is "liveness" and what is "connection"?  Please define these
terms or point to the defintions in other documents. (I have looked
and have not found a precise definition.)

Note: later in document:

   Continuity checks are used to verify the liveness of a connection or
   a path between two MPs, and are typically sent proactively, though
   they can be invoked on-demand as well.

Here "path" and "connection" are used interchangably.   

   o Connectivity Verification (CV):
      Allows an MP to check whether it is connected to a peer MP, and to
      verify that messages from the peer MP are received through the
      expected path.

what is "connected to a peer"? Does that mean "there is a working
path?" Or something else?

   o Path Discovery / Fault Localization:
      An MP uses this mechanism to trace the route to a peer MP, i.e.,

s/the route/the path/ ???

      to identify the nodes along the path to the peer MP. When a
      connection fails, this mechanism also allows the MP to detect the
      location of the failure.

   o Performance Monitoring:
      Consists of 3 main functions

        o Loss Measurement (LM) - monitors the packet loss rate of a
          connection.

what is "connection" in the context of technologies like TRILL (or IP
for that matter)?, which do hop-by-hop forwarding and/or may do load
balancing via ECMP?

   o "Ping" mode: In this mode LSP ping is used for end-to-end
      connectivity verification between two LERs.

What's an LER?

Thomas