Re: [manet-dlep-rg] Latency

I think 16 seconds delay is going to be too small - some HF radios with clever IP implementations can have enormous latency, someone might try using this in DTNs - Mars is more than 16 seconds away I think ;)

Also, if there are radios that might need microseconds then we should specify them.

Perhaps you should ignore me and stick with 32bits microseconds - that's 71 minutes if my rough calculation is correct, and the sun is only 8 light minutes away, and I don't think we need to panic about saving 2 bytes on the wire.

Rick Taylor

> -----Original Message-----
> From: manet-dlep-rg-bounces@ietf.org [mailto:manet-dlep-rg-
> bounces@ietf.org] On Behalf Of Henning Rogge
> Sent: 12 November 2013 16:27
> To: Taylor, Rick
> Cc: DLEP Research Group (manet-dlep-rg@ietf.org); Teco Boot; Stan Ratliff
> (sratliff)
> Subject: Re: [manet-dlep-rg] Latency
>
> I am not worried about the accuracy but that some radios with a strict
> TDMA might fall below the 1ms delay.
>
> But millisecond precision might be good enough.
>
> Is 16 Bit in milliseconds good enough (up to 16 seconds delay) ?
>
> Henning Rogge
>
> On Tue, Nov 12, 2013 at 5:18 PM, Taylor, Rick <Rick.Taylor@cassidian.com>
> wrote:
> > I agree microseconds makes more sense numerically, but does it make
> sense from a latency recording sense, can we really ask for microsecond
> accuracy?
> >
> > I leave it to you guys to advise...
> >
> > Rick Taylor
> >
> >> -----Original Message-----
> >> From: manet-dlep-rg-bounces@ietf.org [mailto:manet-dlep-rg-
> >> bounces@ietf.org] On Behalf Of Henning Rogge
> >> Sent: 12 November 2013 15:59
> >> To: Taylor, Rick
> >> Cc: DLEP Research Group (manet-dlep-rg@ietf.org); Teco Boot; Stan
> Ratliff
> >> (sratliff)
> >> Subject: Re: [manet-dlep-rg] Latency
> >>
> >> 32 Bit and "milliseconds" would be a little bit much I think...
> >>
> >> I was thinking about 32 Bit MICROseconds... would still allow for a
> >> delay of more than one hour.
> >>
> >> Henning Rogge
> >>
> >> On Tue, Nov 12, 2013 at 4:52 PM, Taylor, Rick
> <Rick.Taylor@cassidian.com>
> >> wrote:
> >> > 32 bit ms sounds good to me.
> >> >
> >> > I wasn't suggesting X*hopcount was a good way of reporting latency, I
> >> was just giving you insight into a personal hack ;)
> >> >
> >> > I think there is a general rule that should be covered by the 'Best
> >> Effort' statement:  In a multi-hop mesh, the metrics must reflect the
> fact
> >> it is multi-hop in a 'Best Effort' way.  That includes Latency, which I
> >> would consider a cumulative metric.
> >> >
> >> > Rick Taylor
> >> >
> >> >> -----Original Message-----
> >> >> From: manet-dlep-rg-bounces@ietf.org [mailto:manet-dlep-rg-
> >> >> bounces@ietf.org] On Behalf Of Stan Ratliff (sratliff)
> >> >> Sent: 12 November 2013 15:34
> >> >> To: Henning Rogge
> >> >> Cc: DLEP Research Group (manet-dlep-rg@ietf.org); Teco Boot; Taylor,
> >> Rick
> >> >> Subject: Re: [manet-dlep-rg] Latency
> >> >>
> >> >>
> >> >> On Nov 12, 2013, at 10:27 AM, Henning Rogge <hrogge@googlemail.com>
> >> wrote:
> >> >>
> >> >> > How much resolution do we need?
> >> >> >
> >> >> > It milliseconds enough, or do we need to do better? Maybe 32 bit
> >> >> > integer in microseconds? That would give us enough precision but
> also
> >> >> > allows for high-delay radios.
> >> >> >
> >> >> > *looking at Stan's reply* rolling latency sounds reasonable, so
> its
> >> >> > similar to the "control package RTT" Rick Taylor told us about?
> >> >> >
> >> >> > So we are looking for a value that means "rough estimate of the
> time
> >> >> > between IP packet got delivered to radio and IP packet leaves
> other
> >> >> > radio" ?
> >> >>
> >> >> That sounds right to me.
> >> >>
> >> >> Regards,
> >> >> Stan
> >> >>
> >> >> >
> >> >> > Henning Rogge
> >> >> >
> >> >> > On Tue, Nov 12, 2013 at 2:43 PM, Taylor, Rick
> >> >> <Rick.Taylor@cassidian.com> wrote:
> >> >> >> From my experience:
> >> >> >>
> >> >> >> My test DLEP devices just make up a number (not very helpful)
> >> >> >>
> >> >> >> The radios I have used that support DLEP-00 natively report a
> >> latency
> >> >> in ms.  What that really is I have no idea.  Again, not very useful.
> >> >> >>
> >> >> >> I have my own DLEP proxy for some other radios, and I have just
> >> >> reported half of RTT on my control packets, which given I have
> jitter
> >> and
> >> >> back-off, again isn't very useful.
> >> >> >>
> >> >> >> BUT, Having a latency metric, even if it is almost meaningless,
> is
> >> >> better than no metric at all.
> >> >> >>
> >> >> >> I could suggest 100ms * hop-count works in mesh radios, as one of
> >> the
> >> >> simplest uses of latency is as an improved hopcount for split-
> >> horizoning
> >> >> in routing protocols.
> >> >> >>
> >> >> >> It's amazing what one will try to use, even if the quality of the
> >> data
> >> >> is very poor!
> >> >> >>
> >> >> >> Rick Taylor
> >> >> >>
> >> >> >>> -----Original Message-----
> >> >> >>> From: manet-dlep-rg-bounces@ietf.org [mailto:manet-dlep-rg-
> >> >> >>> bounces@ietf.org] On Behalf Of Henning Rogge
> >> >> >>> Sent: 12 November 2013 13:23
> >> >> >>> To: Teco Boot
> >> >> >>> Cc: DLEP Research Group (manet-dlep-rg@ietf.org); Stan Ratliff
> >> >> >>> Subject: Re: [manet-dlep-rg] Latency
> >> >> >>>
> >> >> >>> Yes, I heard this too in the MANET Meeting...
> >> >> >>>
> >> >> >>> which made me wonder a bit because I was puzzled what was the
> >> >> >>> difference between the two.
> >> >> >>>
> >> >> >>> Can maybe the people who already have an implementation for DLEP
> >> tell
> >> >> >>> us what kind of Latency they implemented?
> >> >> >>>
> >> >> >>> Henning Rogge
> >> >> >>>
> >> >> >>> On Mon, Nov 11, 2013 at 5:15 PM, Teco Boot <teco@inf-net.nl>
> wrote:
> >> >> >>>>
> >> >> >>>> Op 11 nov. 2013, om 01:55 heeft Stan Ratliff (sratliff)
> >> >> >>> <sratliff@cisco.com> het volgende geschreven:
> >> >> >>>>
> >> >> >>>>> Point 11 - I didn't hear that. Really, I didn't hear any
> >> conclusions
> >> >> >>> about Latency. Other opinions?
> >> >> >>>>
> >> >> >>>> We discussed it and all speakers said it is an important
> metric,
> >> so
> >> >> it
> >> >> >>> will be an optional TLV in core document.
> >> >> >>>>
> >> >> >>>> Wasn't Henning tasked with verifying Latency and EFT?
> >> >> >>>>
> >> >> >>>> Teco
> >> >> >>>>
> >> >> >>>> _______________________________________________
> >> >> >>>> manet-dlep-rg mailing list
> >> >> >>>> manet-dlep-rg@ietf.org
> >> >> >>>> https://www.ietf.org/mailman/listinfo/manet-dlep-rg
> >> >> >>>
> >> >> >>>
> >> >> >>>
> >> >> >>> --
> >> >> >>> We began as wanderers, and we are wanderers still. We have
> lingered
> >> >> >>> long enough on the shores of the cosmic ocean. We are ready at
> last
> >> to
> >> >> >>> set sail for the stars - Carl Sagan
> >> >> >>> _______________________________________________
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> lingered
> >> >> > long enough on the shores of the cosmic ocean. We are ready at
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> >> to
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> >> >>
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> >> --
> >> We began as wanderers, and we are wanderers still. We have lingered
> >> long enough on the shores of the cosmic ocean. We are ready at last to
> >> set sail for the stars - Carl Sagan
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> long enough on the shores of the cosmic ocean. We are ready at last to
> set sail for the stars - Carl Sagan
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