RE: AS7018 upstream loss via 32.130.88.22 (SF Bay Area) — per-flow, unidirectional

["BEASLEY, JOSH via NANOG" <nanog () lists nanog org>]

Hey Mike,

I took a look and I did find a link that needed some attention. I have removed it from the path while the transport 
team works on it. Let me know if you are still seeing an issue.

Josh

From: mikecika--- via NANOG <nanog () lists nanog org>
Sent: Monday, August 24, 2026 9:16 PM
To: nanog () lists nanog org
Cc: mikecika () gmail com
Subject: AS7018 upstream loss via 32.130.88.22 (SF Bay Area) — per-flow, unidirectional

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


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?

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