NTP Requirements

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NTP Requirements
IETF 71 TICTOC Karen ODonoghue karen.odonoghue_at_
navy.mil
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• What I was asked to do
• Discuss NTPv5 requirements
• What I am prepared to address today
• What are the current NTP objectives?
• What is the starting point for the requirements
  for a generic Internet timing protocol?
• What are some of the proposals or topics being
  discussed amongst the NTP community for further
  development.
• What are the next steps from an NTP perspective

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Current NTP Objectives

• As specified in the (expired) draft-ietf-ntp-reqs-
  01 document
• Provide the best accuracy possible given network
  and server conditions
• Resist failures including malicious attacks and
  implementation bugs
• Be robust by utilizing Internet diversity and
  redundancy
• Automatically organize the subnet topology for
  best accuracy and reliability
• Perform host authentication, independent of
  non-NTP services

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• Because of the generic nature of NTP and the
  underlying infrastructure, there are no
  performance requirements specified in the current
  protocol
• Experience has shown
• 10s ms in the wide area
• 1 ms in the local area
• Better than 1 ms in an engineered environment
• TICTOC charter indicates that we want to go
  beyond what is currently available.
• Need some additional rigor to define what is
  available and what is required

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(Very) Generic Requirements

• Improved synchronization performance
• Need definitions of what this means for various
  applications
• Independent of the underlying network
• Scalable
• Fault Tolerant
• Manageable
• Secure
• (Clearly, this list need to be flushed out in
  more detail.)

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Scalability Requirements

• What are the scalability requirements?
• Number of clients/slaves supported
• Number of servers/masters available
• Number of network or infrastructure devices
• Clock (tod and/or freq) aware (e.g. transparent
  clocks)
• Non-clock (tod and/or freq) aware
• Mixture
• Number and types of networks traversed
• Logical and Geographic distance
• Available bandwidth

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Discussed Extensions for NTPv4

• Proposed modifications and improvements to NTP
• Increased polling interval option
• Timestamp location definition
• NTP follow-up message
• Additional authentication mechanism (improved
  security)
• Alternative algorithms
• NTP management and control
• Operational guidance (suggested BCP)
• Discussion deferred by the NTP WG pending
  completion of the core set of specifications
• Some of this is already being implemented

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• To Do (from a requirements perspective)
• Distill the characteristics of NTP into
  requirements
• A next generation solution must do at least
  these
• Identify additional requirements from various
  application communities

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• Comments ?