AGIS Route Flaps Interrupting its Peering?

Rebecca L. Nitzan nitzan at
Fri Jul 5 19:09:44 UTC 1996

Peter et al:

    We too have had nothing but trouble with the netedge boxes
(to mae-east and mae-west).  They are particularly insidious 
when they are "kind of working".  A couple years ago, when traffic 
loads were lower, they seemed to perform well. Does anyone know if
MFS has plans to address this problem?
			-- Becca

Rebecca L. Nitzan                        Lawrence Berkeley National Lab
Network Engineering Services Group       1 Cyclotron Rd, 50A/3101 MS 50C
ESnet - Energy Sciences Network          Berkeley, CA. 94720
phone: 510-486-6468 fax: 510-486-4300    nitzan at

>Here's some background:
>AGIS's router is not colocated at the MAE parking garage, but is in fact
>colocated at WorldCom in downtown Washington DC.  Our bits get from there to
>the MAE via a DS3, and that DS3 is terminated at each end with a device
>called a NetEdge, which does the FDDI to DS3 ATM conversion.
>These NetEdges seem to have three different possible operating states:
>completely working (which doesn't happen often enough); broken (often, right
>out of the box); and kind of working (which happens all too often).  This
>third operating state results in some very interesting, possibly misleading,
>and sometimes damaging behavior.  It looks quite similar to the kind of
>behavior you get when you change the MAC layer device but keep the same ip
>address at either of the MAE's: ARP caches get inconsistent, and BGP
>sessions with other routers flop around, leading to routes getting flap
>dampened by those running the appropriate code.
>Here's what happened:
>AGIS's connection to MAE-East experienced one of these kind-of-working
>problems which resulted in the erratic behavior above.  Digex customers
>wishing to reach AGIS customers called the Digex NOC, and the posting which
>started this all was made to the Digex internal news group.  Similarly, AGIS
>customers had problems, and we worked with MFS to get the problem resolved
>(they must have a warehouse full of swapped-out NetEdges at this point).
>In the interval, a short-on-facts bozo spit into the wind and got us and
>Digex wet.  I'm in private correspondence with Ed Kern to postmortem the
>  Peter
>At 10:25 AM 7/5/96 -0400, Ed Kern wrote:
>>> One key point is that we have not received any complaints or reports
>>> of any sort concerning any perceived issues at mae-east from any
>>> mae-east peers.  Digex made no attempt to contact us.  We were already
>>> working with Advantis on the unreachable issue above, but the first we
>>> heard of the "AGIS attacks mae-east" report was when a Digex customer
>>> sent us a report similar to that forwarded to all of you by Cook.
>>Went into this in the last message...Digex will try and be more
>>proactive with pointing out Agis flapping prefixes in the future.
>>> An appropriate audience would have been the AGIS noc and the Digex
>>> noc.  I think the Cook approach was inappropriate because the issue
>>> was purely between Digex and AGIS until Cook distributed it to the
>>> three widespread mailing lists.
>>I agree..
>>> >   How is the report flawed?
>>> I see that Ed Kern has already replied indicating that the report was
>>> indeed flawed.  I don't think that there is anything to be gained by
>>> going into further detail.
>>What I was referring to was the internal circulation here...which I was
>>under the impression got to external im not so
>>The internal report was flawed because it relied to much on source
>>routes and came to some bad conclusions on the internal state of agis.
>>> My key point is that nothing of interest happened.  This was a
>>> non-issue until the misinformation was blasted around the Internet
>>> technical universe.
>>I would argue that the external message that got sent around was
>>misinformation...It was correct information from what the people
>>could see at the time it was released...(lots of dampened prefixes and
>>a down peer)..
>Peter Kline  Senior Network Engineer|                    313-730-5151
>AGIS - Internet Backbone Services   |                _Lucem Diffundo_
>Post-Traumatic Success Disorder+    |
>You can pretend to care, but you can't pretend to be there.

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