Subject: [trill] TRILL OAM Requirements: Connectivity

From: Thomas Narten <[email-masked]>
Date: Thu, 26 Apr 2012 15:39:12 -0400

draft-tissa-trill-oam-req-00.txt has the following definition:

>    Connected: The term connected is used to indicate reachability; RB2
>    is connected to RB1 implies that RB2 is reachable from RB1.

This is an unituitive definition to me. In my mind, "connected" means
two device are (essentially) separated by a wire. Or, a node is
"connected" to a network. I.e,. the two nodes are neighbors.

Where does this definition of "connected" come from? Is this taken
from somewhere else? Or is this a new definition for TRILL OAM?

Why not use a term like "reachable"?

Later, one of the requirements is:

>    OAM MUST have the ability to verify an RBridge RB1 is connected to a
>    specific RBridge RB2.

Given the above defintion, the usage of the term "connected" above is
murky to me. The definitions section uses "connected" in a much
broader sense than two neighbors being directly attached.

Is the above requirement that RB1 be able to verify it is a neighbor
of RB2 (and has connectivity?)?

Or, if the requirement is testing connectivity between arbitrary RBs,
how is that different from other requirements that relate to path
verification?

>    OAM MUST provide functions that enable an RBridge to perform a
>    Continuity Check to any other RBridge over a specified path or a set
>    of paths.

This section uses "continuity check", which seems like a more precise
term than "connected". 

Thomas

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From: Erik Nordmark <[email-masked]>
Date: Fri, 27 Apr 2012 09:29:32 -0700

> from somewhere else? Or is this a new definition for TRILL OAM?

When I read the document yesterday the "connected" term made me stumble 
as well.
If this is a well-defined term in other OAM standards, then we should 
include that definition in the terminology section so that it can be clear.
If it is not, then lets use a term that is more clear.

    Erik