All,
Participting in a severe solar event EXERCISE. Can anyone give me an
educated guesstimate of the percentage of backbone traffic that is
satellite dependent vs. that which is totally land-based?
Thanks
Kevin Smith
Information Systems & Services
Department of Community Affairs
kevin.smith@dca.state.fl.us [preferred]
850.922.9921 [voice]
850.487.3376 [fax]
Depends on the country. I suspect in the USA, it's close to 100% land-based.
In places in central Africa, it's probably close to 100% satellite based.
Simon
Kevin,
Satellite transport is common mainly in areas where land based
infrastructure is not feasible. In developed nations this is almost
exclusively the case. Satellite latency is far too high to rely on it
for routine communications unless used as a last resort.
Best regards, Jeff
The last FCC statistics I found researching this last year.
2006
Satellites carry 0.22% of US international circuits. There are 14,346 US
international circuits via satellite.
Jeffrey,
While technically you are correct, I would say that you probably should also add a category for mobile communications LAND/SEA/AIR. The traffic for these will be increasing in time as vendors are starting to put switches and routers on-board spacecraft making applications that were once borderline, because of delay, more acceptable. Depending on what you are doing (eg. comm between two satellite ground stations, mobile or stationary) the application can benefit from from reduced RTT due to this innovation. One-way delay would thus be about 250ms. This is greater than the generally accepted 150ms for a voice call but with good voice quality 250ms is not bad. This of course is based on GEO sats. LEO or MEO satellites are much closer to the earth so the delay would be less but they present a whole host of other complexities.
While satellites will probably never come close to the volume of ground-based comm, they will cater to niche markets, military, mobile and disadvantaged users.
WRT Kevin's query, if you are concerned about a solar incident and it's affects on satcom, you might want to take a look at what user base (e.g. which mobile users and what impact loss of comm will have on what they are doing) is affected rather than understanding the volumes that are affected as this might provide a much more thorough understanding of any impact. But that is merely my two cents worth.
-Donner
Jeffrey Lyon wrote:
Northern communities in Canada's arctic rely exclusively on satellite
for voice/data.
Not a lot of data flowing comparatively, but it is their only option so
it is more of a "mission critical" thing than a backup.
Yep, consider the Galaxy IV satellite incident. The loss of a single satellite had a significant impact on its user population for several
days/month. Other satellites can be moved into an orbital slot, and
dishes can be re-pointed; but Galaxy IV lead to some interesting (i.e.
unexpected to some users) failures. I'm not sure how many hospitals
realized their "in-house" pager systems relied on a satellite.
JF Mezei wrote:
Northern communities in Canada's arctic rely exclusively on satellite
for voice/data.Not a lot of data flowing comparatively, but it is their only option so
it is more of a "mission critical" thing than a backup.
Also high latitudes are problematic as far as your link budget to
geostationary satellites goes in the first place. Switching to an
alternative satellite in the event of a failure may be more challenging
as a result.
Satellites often sit at the edge of the network. The "orbital last mile" for individual users as well as in-country (Africa for e.g.) ISPs and Enterprise networks. When they go, often there is no backup (except maybe another satellite connection).
Sean Donelan wrote:
Northern communities in Canada's arctic rely exclusively on satellite
for voice/data.
Ditto most Pacific Island nations...
Not a lot of data flowing comparatively, but it is their only option so
it is more of a "mission critical" thing than a backup.
... although most Pacific Islanders I have met who are not on cable routes are somewhat tolerant about multi-week outages, perhaps because the alternative to tolerance is not obvious.
Joe
French Polynesia has no fiber links at all and relies exclusively on satellite and
maybe radio for internet access.
It looks, though, like they may finally get fiber sometime in the next decade :
http://www.newstin.com/tag/us/95233925
Marshall
I lived in a Caribbean country where, at the time, most of their LD traffic
was over satellite. While people didn't like it, there were times that
there was no public off-island access for a few hours at a time. It's just
a fact of life, and people get used to it. Those who don't buy a satellite
phone.
Frank
It depends on where in some cases. Take Greenland for example. Prior to Tele Greenland possibly completing the Greenland Connect cable[1] real soon now (Halifax to Nuuk, Nuuk to Iceland, branched to Qaqortoq, with xcon to UK and Denmark) I seem to recall that a large amount of their capacity was via satellite from Godthab(Nuuk) to Denmark.
In this case, you're likely talking 100%. Almost all of your remote cases are going to be in a similiar situation ie. Svarlsbad, most stuff above t~N60^ parallel (or so) etc.
[1] Tele Greenland IT News Item (see last paragraph, Brian Buus Pedersen is Tele's CEO)
Best,
Martin Hannigan
When I was working with Svalbard, Internet connectivity was through a satellite link at about 2.5 degrees
elevation looking through a notch in the mountains. I don't think it has changed
Regards
Marshall
When I was working with Svalbard, Internet connectivity was through a
satellite link at about 2.5 degrees
elevation looking through a notch in the mountains. I don't think it
has changed
It has. Svalbard now has undersea cable connection to the Norwegian
mainland. See
Svalbard Undersea Cable System - Wikipedia
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
At least in the US, satellite use is fairly limited compared to fiber
and copper,
mainly in the following areas
- TV broadcast
- Data and voice to remote areas (a few hundred Alaska villages,
some connectivity up to oil drilling areas in Alaska, though
there's also fiber,
plus some Internet in non-wired parts of the US. I'm not aware of regular
telco use of satellites for service in the middle 48 states. Is Alohanet or
something like it still running in Hawaii?)
- Some emergency backup applications such as restoration for carriers
(redundant cables are nice, but you need access in multiple failure scenarios
such as floods and earthquakes.)
- Specialized enterprise applications (some years ago, VSAT was fairly common
for credit-card support at gas stations, malls, etc. I know one
grocery store chain
that finally moved to terrestrial in the late 90s, forced by
Microsoft application protocols
that couldn't handle the VSAT latency.)
Marshall Eubanks <tme@multicasttech.com> writes:
When I was working with Svalbard, Internet connectivity was through a
satellite link at about 2.5 degrees
elevation looking through a notch in the mountains. I don't think it
has changed
It has, as Steinar says.
For those interested in the necessary elevation at 78 degrees north, I
found a nice picture of the antennas here:
http://www.mydarc.de/la0by/isfjord.jpg
There aren't any mountains in front of the the antennas. However there
is a mountain between Isfjord Radio and Longyearbyen (the main
settlement), requiring a relay station on the radio link between these.
Bjørn
Marshall Eubanks <tme@multicasttech.com> writes:
When I was working with Svalbard, Internet connectivity was through a
satellite link at about 2.5 degrees
elevation looking through a notch in the mountains. I don't think it
has changedIt has, as Steinar says.
For those interested in the necessary elevation at 78 degrees north, I
found a nice picture of the antennas here:
mein.DARCThere aren't any mountains in front of the the antennas. However there
is a mountain between Isfjord Radio and Longyearbyen (the main
settlement), requiring a relay station on the radio link between these.
The NyAlesund SGO
http://siempre.arcus.org/4DACTION/wi_alias_fsDrawPage/1/107
is some distance North of Longyearbyen (how many places can say that ?), and I used to have
a nice picture, which alas I cannot find, of the satellite link (not the 20 meter dish in the picture) apparently pointing at the mountains.
It does indeed have fiber now, and has been used for eVLBI
Regards
Marshall
