Snipped …
>Shraddha, you've said
>"The measurement mechanisms and advertisements in ISIS support micro-second
>granularity (RFC 8570)."
>Could you direct me to the text in RFC 8570 that defines the measurement
>method, protocol that limits the >resolution to a microsecond?
Pls refer RFC 8570 sec 4.1. The link delay is encoded in microseconds
“ Delay: This 24-bit field carries the average link delay over a
configurable interval in microseconds, encoded as an integer
value. When set to the maximum value 16,777,215
(16.777215 seconds), then the delay is at least that value and may
be larger.
“
Exact same text can be found in OSPF RFC 7471 sec 4.1.5 as well.
Rgds
Shraddha
Juniper Business Use Only
From: Lsr <[email protected]> On Behalf Of [email protected]
Sent: Tuesday, May 25, 2021 8:03 AM
To: [email protected]
Subject: Re: [Lsr] LSR WG Adoption Poll for "Flexible Algorithms: Bandwidth,
Delay, Metrics and Constraints" - draft-hegde-lsr-flex-algo-bw-con-02
[External Email. Be cautious of content]
Dear All,
thank you for the discussion of my question on the unit of the Maximum Link
Delay parameter.
Firstly, I am not suggesting it be changed to a nanosecond, but, perhaps, 10
nanoseconds or 100 nanoseconds.
To Tony's question, the delay is usually calculated from the timestamps
collected at measurement points (MP). Several formats of a timestamp, but most
protocols I'm familiar with, use 64 bit-long, e.g., NTP or PTP, where 32 bits
represent seconds and 32 bits - a fraction of a second. As you can see, the
nanosecond-level resolution is well within the capability of protocols like
OWAMP/TWAMP/STAMP. As for use cases that may benefit from higher resolution of
the packet delay metric, I can think of URLLC in the MEC environment. I was
told that some applications have an RTT budget of in the tens microseconds
range.
Shraddha, you've said
"The measurement mechanisms and advertisements in ISIS support micro-second
granularity (RFC 8570)."
Could you direct me to the text in RFC 8570 that defines the measurement
method, protocol that limits the resolution to a microsecond?
To Acee, I think that
"Any measurement of delay would include the both components of delay"
it depends on where the MP is located (yes, it is another "It depends"
situation).
I agree with Anoop that it could be beneficial to have a text in the draft that
explains three types of delays a packet experiences and how the location of an
MP affects the accuracy of the measurement and the metric.
Best regards,
Greg Mirsky
Sr. Standardization Expert
预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D
Institute/Wireline Product Operation Division
[cid:[email protected]]
[cid:[email protected]]
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