TICTOC Tim Frost,
Internet Draft Greg Dowd,
Intended status: Informational Symmetricom, Inc.
Expires: January 5, 2011
Laurent Montini,
Cisco Systems
July 5, 2010
Management Requirements for Packet-based Timing Distribution
draft-frost-tictoc-management-00.txt
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Abstract
This Internet draft investigates the management aspects associated
with packet-based distribution of time and frequency using protocols
such as PTP (Precision Time Protocol, [1]). It explores some of the
issues that need to be solved in connection with the management of
synchronization distribution.
Table of Contents
1. Introduction...................................................2
1.1. Elements of synchronization management ....................3
1.2. Use of a single synchronization management domain .........3
2. Issues to be resolved..........................................3
2.1. What information must be maintained by synchronization
functions? ................................................4
2.2. What performance data related to the timing flow are to
be collected? .............................................4
2.3. What alarms must be generated by synchronization
functions? ................................................4
2.4. How is the management data to be collected? ...............5
2.5. Identification of network elements containing
synchronization functions .................................5
3. Security Considerations........................................5
4. IANA Considerations............................................6
5. Acknowledgements...............................................6
6. Informative References.........................................7
Author's Addresses................................................7
1. Introduction
Synchronization for many telecoms applications (e.g. wireless
basestations, circuit emulation services) is a mission-critical
service, in the sense that if the synchronization service goes out
of tolerance, the enabled service may fail, impacting revenue. When
the synchronization is delivered by a packet-based mechanism (e.g.
by use of PTP defined in [1]), continuous in-service monitoring is
required to verify the quality and traceability of the
synchronization.
The purpose of this draft is to examine some of the requirements of
synchronization management and to propose options for how these
issues may be tackled. It has been developed out of the informal
"Problem Statement for Management of Synchronization Networks"
presented at IETF 77.
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1.1. Elements of synchronization management
Elements in effective management and monitoring for packet-based
synchronization distribution include:
o Fault monitoring and reporting
o Performance and status monitoring of the synchronization
equipment
o Performance and status monitoring of the packet network related
to timing distribution
Analysis of the performance data for trends in key synchronization
performance indicators may allow "early warning" of possible issues
(e.g. congestion) that may affect synchronization. Continuous, in-
service monitoring enables the operator to be informed of events or
trends likely to affect the synchronization network and enable
corrective action to be taken.
1.2. Use of a single synchronization management domain
Whilst distributed across the network, and possibly embedded into
disparate network elements, synchronization forms a distinct
infrastructural function within the network. This means it needs to
be planned and managed as an entity, and not as collection of
separate components.
The aggregation of synchronization information and processing of it
as an integrated whole can provide powerful insights into the
overall performance of the synchronization service, and indicate if
more general corrective action is required. For example,
degradation in the key performance indicators of several
synchronization network elements may be an early warning sign of
increased network loading.
Use of specific synchronization node manager can enhance such
holistic management of the synchronization function. It also
simplifies the integration of the synchronization management into an
operator's OSS (Operations and Support System), by providing a
single point of integration with visibility of the whole network,
including the synchronization service, and allowing correlation of
information from multiple network information.
2. Issues to be resolved
Some of the issues that need to be resolved in the creation of a
coherent approach to synchronization management include:
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o What information must be maintained by synchronization functions?
o What performance data related to synchronization are to be
collected?
o What alarms must be generated by synchronization functions?
o How is the management information to be collected?
o How can network elements containing synchronization functions be
discovered?
These issues are discussed in the following sections.
2.1. What information must be maintained by synchronization functions?
A standard set of "synchronization information" should be defined,
such that all synchronization functions are able to report the same
types of information. This should include node information related
to timing and synchronization, protocol-specific information (e.g.
for PTP-based functions, the standard data sets) and timing
performance data, enabling a synchronization network manager to
assess the health of a synchronization node.
The standard set of information should be defined in terms of a MIB
(Management Information Base) for each type of synchronization
function (e.g. packet master or slave clock, or "on-path" timing
support elements).
2.2. What performance data related to the timing flow are to be
collected?
A standard set of information relating to the quality and
performance of the timing packet flow will enable a synchronization
network manager to assess the health of a individual timing path and
of the synchronization network as a whole.
The standard set of information could be defined in terms of a IPFIX
Information Model using IPFIX protocol for collecting the
information from various nodes.
2.3. What alarms must be generated by synchronization functions?
Similarly, a standard set of alarms for synchronization functions
should be defined. These should include conventional alarm criteria
such as input signal failure, as well as more specific packet-based
synchronization criteria, such as the PTSF conditions defined in the
ITU-T's Telecom Profile [2].
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2.4. How is the management data to be collected?
Another consideration is how the data are to be collected. This may
be dependent on the equipment in which the synchronization functions
are embedded, the type of information, and the operator's own
management strategy. Some potential options include:
o through a management channel in the synchronization flow (e.g.
PTP management messages), to a synchronization network manager
o through a management channel distinct from the synchronization
flow (e.g. SNMP or IPFIX protocols)
o through the element management system of a network element
containing a synchronization function, and then northbound into
the OSS
o through the element management system of a network element
containing a synchronization function, and then northbound into a
synchronization network manager
2.5. Identification of network elements containing synchronization
functions
One of the main issues is to identify network elements containing
synchronization functions. A synchronization network management
system can only manage devices that it knows exist, and in a large
network, it may be difficult to discover which network elements
contain synchronization functions.
This identification process is not strictly speaking a management
function, but it is relevant and necessary to enable on-going
synchronization management. Some options for identification of
synchronization functions include:
o synchronization function identifies itself to a pre-configured
synchronization management node on startup
o synchronization masters or servers maintain a list of their
currently serviced slaves/clients, and make the list available
for the synchronization network manager to query.
3. Security Considerations
Security aspects of the above options will need to be considered in
more detail.
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4. IANA Considerations
No IANA actions are required as a result of the publication of this
document.
5. Acknowledgements
The authors wish to thank Sanjay Mani (Symmetricom) for his
invaluable comments.
This document was prepared using 2-Word-v2.0.template.dot.
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6. Informative References
[1] IEEE, "Standard for A Precision Clock Synchronization Protocol
for Networked Measurement and Control Systems", IEEE1588-2008.
[2] "ITU-T PTP Profile for Frequency distribution without timing
support from the network ", Draft Recommendation G.8265.1
(work in progress), TD-PLEN-0255-R1, June 2010
Author's Addresses
Tim Frost,
Symmetricom Inc.,
2300 Orchard Parkway,
San Jose,
CA 95131,
USA.
Email: tfrost@symmetricom.com
Greg Dowd,
Symmetricom Inc.,
2300 Orchard Parkway,
San Jose,
CA 95131,
USA.
Email: gdowd@symmetricom.com
Laurent Montini,
Cisco Systems,
11, rue Camille Desmoulins,
92782 Issy-les-Moulineaux,
France.
Email: lmontini@cisco.com
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