AS7170 flaps and resulting non-event

Craig A. Haney craig at
Thu Dec 2 09:21:15 UTC 1999


AT&T-DISC is an AT&T Network that is specifically for DREN/DISC DoD 
Government use.
It is not their public/commercial IP service offering.

What is DREN:


What is DISC:

For a while now I understand this network is working with a skeleton 
operations crew and none of the original architects have been there 
for a long time. And some of the Merit folks that were under contract 
to AT&T DISC as advisors also have left Merit recently.

It is probally best to take up any issues you have with the DISC HELP 
DESK information available at:

They are located either in Vienna, VA off Gallows Rd (right near 
MAE-EAST) or Oakton VA (Down Rt 123 - again near MAE-EAST).

and/or also take up the issue with the Technical Advisory Panel at 
the same time:
And I see that this list is out of date.

hope this helps you getting your concern resolved.


23:22 -0800 12/01/1999, John Todd wrote:
>Starting on the 19th of this month, the Merit routing report shows 
>that AT&T-DISC(AS7170) is having some serious flapping issues with 
>the Merit route server at the MAE-East (ten million updates in a 
>day, as an example.)  Among other things, I'm interested if these 
>flaps are being made to all peers of AS7170 at the MAE-East.  If 
>that is the case, then nobody has noticed, or nobody cares, or 
>nobody has raised it in a public forum yet.  If the silence has been 
>caused by one of the first two situations, I'm interested in which 
>is the true reason that there has been no hue and cry over this 
>abnormal number of route insertions/removals.
>A few questions and items to chew on:
>   1: Is this something that anyone other than Merit is noticing? 
>Could it be that AS7170 just doesn't have that many peers, or that 
>the routes are flapping only to Merit's route server?
>   2: Is this just being dampened to the point where nobody notices?
>   3: Is the silence on this issue somehow indicative of the 
>increased speed/memory of core routers in the North American and 
>other routing structures?  [main point] If so, then this changes 
>some arguments about who and why one will/will not peer, as well as 
>dragging the corpse of "Sprint filtering" out of the grave.[/main 
>   4: Am I just reading this data incorrectly?  I don't have a direct 
>peer with 7170 anywhere, so I can't look at my own records for 
>Side notes:
>   A: This isn't AT&T's only AS number - they have two others (7018 
>and 5075) that seem to be used for quite a few announcements.  In 
>fact, 7170 may not be the "primary" AS for AT&T - again, I don't 
>have a crystal ball to see how they structure their announcements 
>across the multiple AS'es.
>   B: It's not easily possible for me to find which routes were 
>flapping; could this be just a few routes out of the N that 7170 
>announces?  (See 
>ast.7170.view.991128 for an exhaustive list of 7170's routes to 
>Merit on the 28th)  If it's only a few of the routes, then perhaps 
>dampening by peers simply quashed the rogue networks into oblivion 
>without anyone noticing that these few routes were missing.
>   C: Could this be related? 
>  I 
>don't think so, but it's an interesting note nonetheless.  I don't 
>see how DNS could be attached to the route flaps, but again I don't 
>have a crystal ball into AT&T's network.
>I've included selected sections from Merit's daily route flap mail. 
>To see a complete list of the messages, browse to 
> for more 
>Largest Sources of BGP Instability
>(announcements + withdraws = total)
>Dec 01: 1.  AT&T-DISC (AS7170) at Mae-East 10432535 + 36800 = 
>10469335 BGP prefix updates
>Nov 30: 1.  AT&T-DISC (AS7170) at Mae-East 10432535 + 36800 = 
>10469335 BGP prefix updates
>Nov 29: 1.  AT&T-DISC (AS7170) at Mae-East 11122216 + 16465 = 
>11138681 BGP prefix updates
>Nov 28: 1.  AT&T-DISC (AS7170) at Mae-East 10256555 + 17732 = 
>10274287 BGP prefix updates
>Nov 27: 1.  AT&T-DISC (AS7170) at Mae-East 9882016 + 23527 = 9905543 
>BGP prefix updates
>. [similar results in here]
>Nov 19: 1.  AT&T-DISC (AS7170) at Mae-East 2462647 + 93171 = 2555818 
>BGP prefix updates
>[AT&T-DISC does not show up in the mail from the 18th or 17th, 
>leading me to think these flaps started during the measured interval 
>reported on the 19th.]
>jtodd at

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