Re: AS7018 upstream loss via 32.130.88.22 (SF B ay Area) — per-flow, unidirectional

Maybe Josh fixed it, but I'm not seeing packet loss here.
Odd that traceroutes stop at the 32.130...
Because of that I cannot see if I am transiting 32.130.88.22 → 
32.130.20.157 or not.

al@post:/z/dns$ traceroute ibm.com
traceroute to ibm.com (23.203.227.97), 30 hops max, 60 byte packets
  1  routr0.sunnyside.com (192.147.248.2)  0.114 ms  0.139 ms *
  2  12.250.77.157 (12.250.77.157)  3.149 ms  3.177 ms  3.208 ms
  3  cr82.sj2ca.ip.att.net (12.122.128.202)  4.583 ms  4.602 ms 4.598 ms
  4  ggr6.la2ca.ip.att.net (12.122.128.33)  2.938 ms  3.121 ms  3.207 ms
  5  12.122.149.46 (12.122.149.46)  7.381 ms  7.404 ms  7.397 ms
  6  12.122.149.225 (12.122.149.225)  6.951 ms  6.787 ms  6.781 ms
  7  32.130.25.168 (32.130.25.168)  5.354 ms * *
  8  * * 32.130.20.158 (32.130.20.158)  4.423 ms
  9  32.130.104.99 (32.130.104.99)  4.816 ms  4.805 ms  4.792 ms
10  * * *
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * * *
30  * * *
al@post:/z/dns$ ping -4 ibm.com
PING ibm.com (23.203.227.97) 56(84) bytes of data.
64 bytes from a23-203-227-97.deploy.static.akamaitechnologies.com 
(23.203.227.97): icmp_seq=1 ttl=53 time=5.69 ms
64 bytes from a23-203-227-97.deploy.static.akamaitechnologies.com 
(23.203.227.97): icmp_seq=2 ttl=53 time=5.70 ms
^C
--- ibm.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 5.690/5.696/5.703/0.075 ms


On 8/24/2026 19:15, mikecika--- via NANOG wrote:
> Seeing sustained upstream packet loss on AT&T Fiber (AS7018) in the SF Bay Area that looks path-dependent rather than congestion or CPE related. Posting in case anyone at AT&T can take a look, or has seen the same.
>
> Symptoms:
>
> Upstream collapses to ~2–5 Mbps on a 1 Gbps symmetric circuit
> Downstream unaffected — 219 measured transfers, 0 failures
> Host TCP counters show 5–14% retransmission on affected flows
> Per-flow: back-to-back transfers to the same destination, differing only in source port, alternate between full rate and collapsed. Once a flow establishes it stays in whichever state it started in.
>
> Affected destinations traverse 32.130.88.22 → 32.130.20.157. Destinations routing otherwise are unaffected (12 tested, 0 failures).
>
> Ruled out: CPE (3 gateways, 2 models), plan tier (5G → 1G), optics (no DDM alarms, PON O5), MTU (0% ICMP loss at all sizes), Wi-Fi (wired throughout).
>
> ~650 measurements over 7 days. Traceroutes and per-destination breakdown available on request.
>
> Anyone else seeing this on AS7018 in the Bay Area?
> _______________________________________________
> NANOG mailing list
> https://lists.nanog.org/archives/list/[email protected]/message/ESBPA7A4QTSLZZ6VQFYEPN25MQLKSV5L/

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