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(Continuation of Question 6/13 studied during 1997-2000)
Background and justification
OAM and protection switching issues of IP-based networks are to be
considered. Requirements and issues are to be studied first. After requirements
are decided, IP OAM functions have to be considered.
Concerning the study of IP-based network issues, cooperation with the IETF,
is necessary.
Protection switching in IP-based networks may be useful, for example, to
protect small numbers of premium services which rely on high reliability when
multiplexed with a large number of unprotected services. This issue needs to be
studied. It may also be useful to protect a bundle of connections using group
protection.
Recommendation I.610 was enhanced in the study period 1997-2000; however, it
still does not cover all the OAM aspects for ATM Layer, and some items are still
open. This Recommendation is devoted to Layer management functions of the
Physical and ATM Layers. In order to cover the aspects of maintenance and
management in B-ISDN, not only the ATM Layer management functions but needs for
studies of ATM Adaptation Layers (AALs) and other evolving link layer management
also have to be considered.
Recommendation I.630 was published in the study period 1997-2000. The current
version only covers point to point 1+1 and 1:1 protection. In order to improve
the bandwidth efficiency, 1:n and m:n architecture needs to be considered as
well as ATM ring protection.
Items for study
1) Items related to OAM and protection switching for IP-based networks
a) Clarification of the necessity of OAM for IP-based network
b) Clarification of the necessity of performance measurement functions for
IP-based networks
c) Clarification of the necessity of bi-directional OAM functions
d) Clarification of whether all NEs should be connected to TMN
e) Clarification of whether a similar technology on ATM layer or SDH layer
be applied to MPLS
f) Definition of IP OAM functions based on the above requirements.
g) Identifying the need for protection switching for IP-based networks.
h) Study the relationships between rerouting and protection switching in
IP-based networks
2) Items related to B-ISDN OAM and protection switching
a) ATM Layer network configuration management. It is necessary to take
account of VP/VC configurations, especially when functions are used which
change VP/VC configuration dynamically, such as ATM Layer protection
switching. It has to be clarified how this management can be done, what
functionality is needed and what are the requirements for this capability.
b) Management of Switched Virtual Connections (SVCs).
c) ATM OAM principles and network management for Point-to-Multipoint
connections. Investigate the implications of the support of
Multipoint-to-Point connections on OAM at the ATM Layer Level.
d) ATM OAM in case of service interworking and network interworking.
e) Need for AAL OAM.
f) Relationship between B-ISDN OAM and resource Management capabilities.
g) ATM Layer failure localization. Clarify whether existing OAM procedures
are sufficient or should be amended for providing this basic OAM requirement.
h) OAM cell Identifier fields. Give guidance on how to use identifiers for
OAM purposes (e.g. AIS, RDI, loopback...).
i) OAM functions to support Performance and Availability Parameters
measurements. In particular, clarify how existing OAM procedures could be used
for the types of QoS classes services where CLR parameters are unbounded (i.e.
class 3 and unspecified class).
j) Definition of functions implementing measurements and observation of
theoretical Performance Parameters. Trade-off between precision and
effectiveness has to be considered (with Questions 6 and 7/13).
k) Protection switching with 1:n and m:n architecture.
l) Semi-dedicated protection switching.
m) ATM ring protection.
n) Clarifying the performance aspects of protection switching.
o) Protection switching against Signal Degrade (SD).
Tasks with deadlines
1. Preparation of Recommendations on OAM functions/protection switching for
IP-based network. (determine by the end of 2002)
2. Revision and enhancement of Recommendation I.610. Improve the
understanding of Recommendation I.610 text with respect to currently defined
optional OAM functions. Clarify the various items related to existing OAM
functions. In particular it has to be considered whether those functions are
suitable for on demand connections (SVCs). Provide guidelines on SVC management
if needed. Specification of relationship between Performance and availability
parameters and OAM flows. OAM functions for Point-to-Multipoint connections need
to be considered. (determine by the end of 2003).
3. Revision and enhancement of Recommendation I.630. In particular, 1:n and
m:n protection configuration, semi-dedicated protection, ATM ring protection,
performance of protection switching and protection against signal degrade (SD)
needs to be considered.(determine by the end of 2001).
4. Other Recommendations on the other evolving link layer management need to
be determined as appropriate.
Relationships
- ITU-T Study Groups on TMN and network management principles and specifications
- ITU-T Study Groups on SVC management;
- ITU-T Study Groups on SDH and ATM TMN architecture and on transport systems and equipment.
- ITU-R Study Groups on broadcasting and mobile aspects
- IETF
- MSF
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