📢 [Network Update – China Unicom Packet Loss in LAX]

We have observed packet loss on EB and Pro routes via China Unicom (AS9929), primarily caused by a DDoS attack targeting AS9929 customers.

China Unicom does not drop attack traffic within China when AS10099 customer announces RTBH (Blackhole). Instead, traffic is blocked only at overseas Provider Edge (PE) routers. If the attack volume exceeds their backbone capacity, packet loss and jitter are unavoidable.

🔒 DMIT has already implemented second-level DDoS detection and automatic RTBH to minimize impact, with victim IPs blackholed in under few seconds. This protects our uplink with AS10099 from congestion.

However, please note:

This cannot prevent packet loss if the attack targets other AS10099 customers.
It is also ineffective if the attack exceeds China Unicom's international backbone capacity (AS9929/AS10099).

China Unicom does not support RTBH natively on AS4837 and instead sells it as a premium service. Even with this feature, we cannot mitigate attacks aimed at unrelated IPs. (like if there is attack to other AS10099 customers.)

Unfortunately, resolution is not possible unless China Unicom changes its policies—which appears unlikely, as the current structure incentivizes selling RTBH as a product.

We appreciate your understanding and we will continue to monitor and mitigate as much as possible on our end.