That's really odd for all of your SS7 services to go down because
carriers typically connect to 2 A-links which are backed up by 2
D-links. So there are a total of 4 STPs (Signaling Transfer Points)
programmed to back each other up. It could be down for one of two
reasons.
In the SS7 network, each switch is assigned a unique point code (9 digit
number that identifies the switch location). In order for the ISUP
trunks to work, the SS7 provider has to establish a route between your
switch and the other carrier's switch. To make it a little easier to
understand let's pretend you have a switch in CA and you are connecting
it to 3 of AT&Ts San Francisco tandems. If each switch had the following
point code assignments:
Your switch's point code: 005-123-456
San Francisco tandem: 222-000-111
Oakland tandem: 222-000-222
Santa Rosa tandem: 222-000-333
Then your SS7 provider would build 3 point code routes:
Your switch 005-123-456 to AT&T San Francisco tandem 222-000-111
Your switch 005-123-456 to AT&T Oakland tandem 222-000-222
Your switch 005-123-456 to AT&T Santa Rosa tandem 222-000-333
When your customer makes a call that is served by the Oakland tandem,
the call would be routed over the 005-123-456 to 222-000-222 route set.
If your links work but the call doesn't complete either your route set
failed for some reason, or either AT&T's SS7 links or trunks went down.
I'd ask them where the failure occurred.
MARY LOU CAREY
BackUP Telecom Consulting
Office: 615-791-9969
Cell: 615-796-1111
On 2022-01-19 04:13 PM, Mike Hammett wrote:
The links have since come back. This is the second major failure of
TNS within 6 months. No RFO yet, but I will certainly be on them for
some detail.
My Metaswitch support rep verified that (pardon my lack of using the
correct terminology, I'm not that familiar with it) our SS7 links
never actually went down, it just lost connectivity beyond that. Sorta
like my BGP peer stayed up, but I lost the global routing table behind
it.
-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com
Midwest Internet Exchange
http://www.midwest-ix.com
-------------------------
From: "Mike Hammett" <[email protected]>
To: "voiceops" <[email protected]>
Sent: Wednesday, January 19, 2022 4:05:32 PM
Subject: [VoiceOps] TNS SS7 Outage
Does anyone have any information on the TNS SS7 outage going on now?
Both of our A-links go to different facilities (Chicago and Ashburn)
over different VPNs (which are up).
TNS has acknowledged that it's a carrier issue. That they're
investigating.
-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com
Midwest Internet Exchange
http://www.midwest-ix.com
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