APC Network Management Cards Network Time Protocol Support NOT!

Discussion in 'Cisco' started by Ed M, Nov 17, 2003.

  1. Ed M

    Ed M Guest

    This is a little off the topic of Cisco equipment but I'm sure a lot of
    people on this newsgroup use APC equipment in their networks.
    We have several APC AP9617 Network Management Cards in UPS's and external
    enclosures for doing UPS and environmental monitoring.
    You can configure these cards to sync their time to an NTP time source (I
    have ours syncing to the nearest Cisco router) but there is one glaring
    problem: the firmware doesn't support automatic daylight savings time
    changes. This means that although the time is within milliseconds of being
    accurate it could be an hour out unless you go into each card twice a year
    and change the time zone. This is done by setting the time zone forward or
    back. For instance if you are physically located in "Eastern Time" you have
    to move the card's time zone to "Atlantic Time-Canada" for half the year.

    I've discussed this with several people from APC at trade shows and on the
    phone and they agreed that this is a surprising omission that should be
    fixed but I just got the definitive word back from APC that there are no
    plans to support automatic Daylight Savings time in their network cards now
    or in the future.

    Am I missing something? How hard is building this into a device that is
    already syncing to an NTP server?
     
    Ed M, Nov 17, 2003
    #1
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  2. In article <g76ub.12192$>,
    Ed M <> wrote:
    :This is a little off the topic of Cisco equipment but I'm sure a lot of
    :people on this newsgroup use APC equipment in their networks.
    :We have several APC AP9617 Network Management Cards in UPS's and external
    :enclosures for doing UPS and environmental monitoring.
    :You can configure these cards to sync their time to an NTP time source (I
    :have ours syncing to the nearest Cisco router) but there is one glaring
    :problem: the firmware doesn't support automatic daylight savings time
    :changes. This means that although the time is within milliseconds of being
    :accurate it could be an hour out unless you go into each card twice a year
    :and change the time zone.

    Why not run in UTC ?
    --
    This signature intentionally left... Oh, darn!
     
    Walter Roberson, Nov 17, 2003
    #2
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  3. Ed M

    Andre Beck Guest

    "Ed M" <> writes:
    >
    > This is a little off the topic of Cisco equipment but I'm sure a lot of
    > people on this newsgroup use APC equipment in their networks.
    > We have several APC AP9617 Network Management Cards in UPS's and external
    > enclosures for doing UPS and environmental monitoring.
    > You can configure these cards to sync their time to an NTP time source (I
    > have ours syncing to the nearest Cisco router) but there is one glaring
    > problem: the firmware doesn't support automatic daylight savings time
    > changes.


    I don't know these cards (I only know other vendor's SNMP adapters to
    UPSs), but why should they need localtime in the first place? I actually
    consider running core network/IT equipment in anything else but UTC a
    bad idea, this easily extends to a UPS. If there is a location where
    UTC should be converted to localtime, this is the management side that
    monitors the adapter and produces logs, charts, a GUI or such. And this
    software will be a lot less complicated and error prone if the time the
    adapter itself runs at is UTC (double conversions are evil).

    > This means that although the time is within milliseconds of being
    > accurate it could be an hour out unless you go into each card twice a year
    > and change the time zone. This is done by setting the time zone forward or
    > back. For instance if you are physically located in "Eastern Time" you have
    > to move the card's time zone to "Atlantic Time-Canada" for half the year.


    The card *has* a time zone configuration, but doesn't apply DST? This
    is indeed damn silly. I know hardware that just lets you configure a
    numeric "timezone" (like +0100 or -0800 or such), in which case manual
    DST is obvious. But if they have named timezones, they should implement
    them correct - this includes DST.

    > I've discussed this with several people from APC at trade shows and on the
    > phone and they agreed that this is a surprising omission that should be
    > fixed but I just got the definitive word back from APC that there are no
    > plans to support automatic Daylight Savings time in their network cards now
    > or in the future.


    So just run them in UTC. That's probably a bit harder for the US than it
    is over here in Europe, but even here, nobody actually has UTC - so we
    all have to live with an offset. But believe me, as soon as your network
    spans more than one time zone, things become a hell of a lot simpler when
    you are just running everything in UTC that is not surfacing to users. If
    the US military learned that, anyone can ;)

    > Am I missing something? How hard is building this into a device that is
    > already syncing to an NTP server?


    It *is* damn hard. Interfacing to NTP is trivial (at least in client
    style SNTP setups, doing NTP *properly* is rather more sophisticated),
    but NTP just speaks UTC. To convert UTC to localtime, a complete
    implementation requires time zone descriptions of all existing time
    zones of the world, including updates of these descriptions as soon
    as something changes. In Europe, Win95 got the DST change wrong in the
    late 90s due to an out-of-date timezone description. It's even more
    dangerous if you just have a ROM with no actual need for upgrade. The
    complete compiled binary "zic" database is 5 MiB on my Linux box,
    this is not something you really want in your appliance IMO (even if
    it is somewhat redundant and might also fit into <2MiB).

    IOS has a nice solution: It allows you to configure rules for just
    the time zone you need. They are less complete and especially have
    no way to deal with historic or future rule changes, but it allows
    you to live with local time for some years without disruption. Then
    again, you can just forget all that stuff and live without any dis-
    ruption (as long as they don't change UTC itself) when just simply
    running UTC. The only somewhat unexpected thing to happen there are
    leap seconds, but NTP should deal with them sufficiently.

    --
    The _S_anta _C_laus _O_peration
    or "how to turn a complete illusion into a neverending money source"

    -> Andre "ABPSoft" Beck +++ ABP-RIPE +++ Dresden, Germany, Spacetime <-
     
    Andre Beck, Nov 19, 2003
    #3
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