Subject: [ippm] Stratum in draft-ietf-ippm-reporting-mib-01.txt

From: "Henk Uijterwaal (RIPE-NCC)" <[email-masked]>
Date: Fri, 29 Nov 2002 16:39:05 +0100 (CET)

Emile,

I almost forgot that I got appointed as volunteer to bring this to the
list.

IIRC, in the latest draft, a field

 IppmSynchronizationEntry ::= 		   SEQUENCE {
				   ippmSynchronizationIndex   Integer32,
				   ippmSynchronizationTime    GMTTimeStamp,
				   ippmSynchronizationStratum Integer32
		   }

 ippmSynchronizationStratum OBJECT-TYPE
		   SYNTAX     Integer32
		   MAX-ACCESS read-only
		   STATUS     current
		   DESCRIPTION
  "The stratum level of the clock computed when the synchronization event
occurs."
		   ::= { ippmSynchronizationEntry 3 }

has been added.

Stratum specifies the number of hops that one is away from a stratum-0 NTP
clock.  While this is an interesting parameter, it is not what one wants
to know.  For example, if I have 3 boxes on my local net, box 1 with a GPS
clock, box 2 synchronized off box 1, and box 3 off box 2, then box 3 will
have stratum=2.  However, if I sync box 3 of a timeserver somewhere on the
other side of the planet, then its stratum will be 1, but obviously, the
accuracy of the time will be less.

What should be in the MIB is a single bit (or more) indicating whether the
local clock has been synchronized and a number indicating the estimated
accuracy of the synchronized clock.  That way, one can calculate the
estimated error in the final result and decide to use the measurement or
not.

Henk

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Henk Uijterwaal                    Email: [email-masked]
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That problem that we weren't having yesterday, is it better? (Big ISP NOC)

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