[82264] in North American Network Operators' Group
RE: London incidents
daemon@ATHENA.MIT.EDU (Brad Knowles)
Mon Jul 11 06:19:11 2005
In-Reply-To:
<OF38C066CB.D5AD9C93-ON8025703B.0034251C-8025703B.00352557@radianz
.com>
Date: Mon, 11 Jul 2005 12:16:34 +0200
To: NANOG <nanog@merit.edu>
From: Brad Knowles <brad@stop.mail-abuse.org>
Errors-To: owner-nanog@merit.edu
At 10:40 AM +0100 2005-07-11, Michael.Dillon@btradianz.com wrote:
> Some of the problems on the mobile networks were the
> result of a protocol to reserve mobile capabilities for
> the emergency services. The police have the authority to
> switch cells to emergency service and then people with
> specially registered SIM cards in their mobile can
> take priority. Presumably, some amount of capacity is
> also held in reserve for these people as well.
Yes, a certain amount of capacity can be placed on reserve for
the holders of priority access SIMs. You only get those issued to
you by the government. This can include critical emergency services
personnel, selected government officials, important members of the
financial services community, etc....
I don't know the specifics of how much capacity is reserved, but
this sort of thing has been done on telecommunications networks for a
long time. Back before cell phones existed, you could have "flash"
traffic on the DDN or even the PSTN, and when placing a flash call
the phone system would disconnect anyone that stood in your way of
getting the connection you wanted.
You had to be using special telephone equipment, or connected to
a special operator with the right equipment, and you had damn well
better be sure that your call was worthy of knocking anyone else off
the network, but the capability was there. Even the President would
normally make his calls at lower than "flash" priority.
There were lower levels of priority that you could also use, but
"flash" was the top one that I heard about.
> I had moved the weekend before and my landline was not
> yet installed. Also, I live near a large hospital. I noticed
> that my mobile didn't function at all even late on Thursday
> unless I left home and travelled a kilometer or two from
> the hospital. Presumably, the cells in this suburban
> location had also been switched to emergency service.
Could be, but I'd be willing to bet it was more a matter of the
cell just being overloaded. Traffic reservation for priority access
SIMs is only going to take a small amount of the bandwidth available.
The problem is that even normal heavy traffic can overload a cell,
and what was seen during the time you're talking about was anything
but "normal heavy".
--
Brad Knowles, <brad@stop.mail-abuse.org>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
SAGE member since 1995. See <http://www.sage.org/> for more info.
