The MPLS WG Archive

[Hiroshi Ohta <ohta.hiroshi@nslab.ntt.co.jp>]

Hello all,

My name is Hiroshi Ohta, the rapporteur on Q.6 of ITU-T SG13 which is
responsible for OAM and protection switching.  I would like to inform you
that ITU-T Q.6/SG13 started to draft a new Recommendation on OAM and
protection switching for IP-based networks.  It was provisionally numbered
Y.17oam.  Please see the attached initial draft.  I would like to welcome
your contributions to the future meetings.  We are planning to have a
meeting as below:

Date: June 26 - June 30, 2000
Place: Ottawa, Canada
Objectives: The main objective is to progress the work on Y.17oam.  Work on
next release of Recs. I.610 and I.630 will be done if time permits.

If you are interested to attend the meeting, please send me an e-mail
before May 29.

Best regards,

Hiroshi Ohta

-----------------------------------

Draft Recommendation Y.17oam

OAM and protection switching for IP-based networks

(Geneva, 200?)

1	Scope
This Recommendation provides requirements and mechanisms for OAM functions
and protection switching for IP-based networks.  It is recognized that OAM
(Operation and Maintenance) functionality is important in public networks
for ease of network operation, for verifying network performance and to
reduce network operating costs. OAM functionality is especially important
for networks in which Quality of Service is an important issue.

2	References
The following ITU-T Recommendations and other references contain provisions
which, through reference in this text, constitute provisions of this
Recommendation. At the time of publication, the editions indicated were
valid. All Recommendations and other references are subject to revision;
all users of this Recommendation are therefore encouraged to investigate
the possibility of applying the most recent edition of the Recommendations
and other references listed below. A list of currently valid ITU-T
Recommendations is regularly published.

[References are to be added (contributions are invited).]

3.	Definitions
to be added (contributions are invited)

4.	Symbols and abbreviations
to be added (contributions are invited)

5.	Requirements for OAM functions and protection switching

5.1	General requirements for IP-based networks
for further study (contributions are invited)

5.2	Requirements for MPLS OAM
It is to be noted that MPLS OAM functionality is not seen as a substitute
for physical layer (e.g. SONET/SDH) OAM functionality. However, MPLS layer
OAM functions may nevertheless be seen as desirable in addition to physical
layer OAM: They will be required whenever OAM functionality is needed that
permits differentiation per individual LSP.  OAM functionality is useful
because

-	it allows the Operator to verify whether Quality of Service guarantees
given in SLAs (Service Level Agreements) are in fact being met by the
connection,
-	it allows the Operator to reduce network operating costs. Long term
statistics show that the costs of operating a public network are higher
than the initial installation costs,
-	it allows the Operator to improve traffic flow/distribution through the
network, and
-	it gives support for improved accounting/billing procedures.

The following is a preliminary list of possible requirements.

1.	in-service verification of connection availability (whether a connection
is "up" or "down") and error performance (counting of lost frames)

2.	in-service verification of delay and delay variation

3.	in-service verification of connection throughput guarantees.

4.	tools for fast and efficient fault detection and fault localization 

5.	tools for efficient network setup and configuration.

6.	Traffic Engineering functionality for load-dependent route selection of
traffic.

7.	measurement of throughput per connection for throughput based billing

8.	detection of violations to a SLA traffic contract that can be given
consideration for billing.

5.3	Requirements for MPLS protection switching
Protection switching for MPLS is useful because it allows the operator to
improve network 
reliability.  Details are for further study (contributions are invited).

6	Mechanisms of OAM functions and protection switching

6.1	General mechanisms for IP-based networks
For further study (contributions are invited).

6.2	Mechanisms of MPLS OAM
Examples of MPLS OAM functionalities are the followings:
-	Fault management and continuity check
-	Loopbacks
-	Performance monitoring

These examples are oriented towards OAM functions defined for ATM networks.
 Note, however, that in defining OAM functions for MPLS networks, the
intention is not necessarily to reapply ATM mechanisms without
modifications.  Different functions may be defined as necessary.

An OAM indicator in the MPLS header could enable a simple differentiation
between user packets and OAM packets in equipment supporting MPLS. Further
study is required to clarify the need for such an OAM indicator and to
identify a suitable encoding.

6.3	Mechanisms of MPLS protection switching
For further study (contributions are invited).

---------- end of draft Y.17oam -----------


Hiroshi OHTA
NTT Network Service Systems Laboratories
Tel: +81 468 59 8840
Fax: +81 468 59 8569
E-mail: ohta.hiroshi@nslab.ntt.co.jp