Subject: [Time] MEP and maintenance domain boundary

From: Qin Wu <[email-masked]>
Date: Mon, 30 Jun 2014 07:52:18 +0000

Hi, Greg:
Thanks for your review to problem statement draft.

http://tools.ietf.org/html/draft-ww-opsawg-multi-layer-oam-01
Section 4 gives an architecture overview of management plane OAM,
You comment on the following quoted sentence
"MEP is a maintenance functional entity that is implemented into
   network entity at the maintenance domain boundary
"

as "Not necessarily, e.g. MEP at Level < 7 in Ethernet Service OAM as CFM or Y.1731".

Are you saying MEP can be placed either at the maintenance domain boundary or within maintenance domain?

Would you like to clarify a little bit on this?

Regards!

-Qin

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From: Huub van Helvoort <[email-masked]>
Date: Mon, 30 Jun 2014 14:58:21 +0200

Hello Qin,

You wrote:

Hi, Greg:

Thanks for your review
to problem statement draft.

Section 4 gives an
architecture overview of management plane OAM,

You comment on the
following quoted sentence

“MEP is a maintenance
functional entity that is implemented into

network entity at the
maintenance domain boundary

”

as “Not necessarily, e.g. MEP at Level < 7 in
Ethernet Service OAM as CFM or Y.1731”.

Unfortunately MPLS-TP has only one MEL, fixed at "7".

Are you saying MEP
can be placed either at the maintenance domain boundary or
within maintenance domain?

First of all you have to correct the expansion of MEP and MIP:

MEP = Maintenance entity End Point

MIP = Maintenance entity Intermediate Point.

MEPs and MIPs that belong to the same Maintenance Entity (ME) are
not

aware of any MEPs or MIPs outside the ME they belong to.

A Maintenance Entity can be any path, tunnel or section in the

network.

So it can exist between domain boundaries (NNIs) but also inside

a domain, or across multiple domains (end-to-end ME).

In section 4 I notice:

MEP is a maintenance functional entity that is implemented
into a Network Element either at the maintenance domain boundary or
in the maintenance domain and can generate, send and receive OAM
packets.

What is the difference between generate and send OAM packets?

MIP is a maintenance functional entity that is implemented
into a Network Element in the maintenance domain and can forward OAM
packets.

A MIP can also respond to OAM messages sent by the source MEP.

Either MEP or MIP may be at different layer and use various
different encapsulating protocols.

This is confusing, as I explained above.
MEPs and MIPs can exist in different layers/technologies.
However in the same layer ME MIPs cannot exist without MEPs.
MEPs and MIPs in the same ME in a layer are not aware of
MEPs and MIPs other ME in the same layer, nor in other layers.

Best regards, Huub.

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