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February 2022

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AT&T Internet (AS7018) <> Tata Communications (AS6453) daily North-West US coast connection drops
by Tristan 02 Feb '22

02 Feb '22

Hello,For the past month or so now, we've been observing severe issues affecting our availability to North-West US coast AT&T users when reaching us through Tata communications.It seems to occur daily, from roughly 4:40 AM UTC and until 7:30 AM UTC, and connections get entirely dropped on their way from AT&T to Tata.The issue might be more extensive geographically and or timespan-wise but that's the specifics we've been able to confirm ourselves.Using global traceroute (and specifically probe 3670, AT&T Sacramento), the issue seems to revolve around 12.122.114.5 [AS7018]. Here's a sample traceroute that is affected in a similar way (ping shows 100% packet loss):traceroute to 203.175.174.246 (203.175.174.246) 64 hops max, 76 byte packets 1 10.0.0.1 (10.0.0.1) [AS???] 8.345 ms 2.064 ms 2.01 ms 2 68.78.72.22 (68.78.72.22) [AS7018] 2.755 ms 2.5789999999999997 ms 3.197 ms 3 * * * 4 71.147.199.98 (71.147.199.98) [AS7018] 20.544 ms 20.274 ms 20.285 ms 5 12.122.160.166 (12.122.160.166) [AS7018] 30.043 ms 28.155 ms 26.833 ms 7 12.122.114.5 (12.122.114.5) [AS7018] 25.962 ms 26.106 ms 26.115 ms 8 * * * 9 * * * 10 * * * 11 * * * 12 * * *255 *Interestingly, the other way around (Tata->AT&T) from a server of ours (which is affected exactly as the traceroute above shows on the AT&T->Tata direction) works just fine, making its way into AT&T's network through 192.205.37.69.We'd hoped things would fix themselves and moved traffic around via other ASNs in the meantime, but it seems that the problem is either not known or at a standstill.Does anyone know something more or have a recommendation as to what we could do to understand what's going on at least?From some unsubstantiated claims I have been given it seems like the issue would be on Tata's side but it's been nothing more than hearsay and a few vague links so far (like Contact request AS 6453 (nanog.org) for example), so I was hoping for something more definitive, or hearing about others encountering similar issues.Thanks,TristanPS: Target host in the example traceroute is not ours nor directly affiliated with us. Please don't go bother them about us, they are merely affected in the same exact way as we are.

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