Bug 203743

Summary:	Networking goes down when running Docker and receiving fragmented IPv4 packets
Product:	Networking	Reporter:	camden.fullmer
Component:	IPV4	Assignee:	Stephen Hemminger (stephen)
Status:	NEW ---
Severity:	normal
Priority:	P1
Hardware:	x86-64
OS:	Linux
Kernel Version:	4.15.0-1032-aws	Subsystem:
Regression:	No	Bisected commit-id:

Description camden.fullmer 2019-05-28 15:49:52 UTC

We are experiencing an issue where our EC2 instances fail instance status checks and completely lose networking because of cellular UDP traffic going to an instance.

It seems that when sending UDP traffic using T-Mobile cellular the packets are fragmented and causes the system to completely lose networking because of this. I have attached the source code for the iOS app that can reliabily reproduce this issue as well as the server code to receive the traffic. The packet capture of the traffic is attached as well. Also important to note that the system only drops networking when Docker is running, but the fragmentation also happens no matter if Docker is installed or not.

It's also worth pointing out that when sending the traffic over Cellular to a local network at our office that the traffic is not fragmented. This makes me think that there is an issue with networking between T-Mobile and AWS.

Base AWS AMI: ami-0a313d6098716f372
Instance Types: g3.4xlarge or c5.2xlarge
Docker GitHub Issue: https://github.com/docker/for-linux/issues/672
iOS app: https://github.com/docker/for-linux/files/3192116/LockUpDemo.zip
Server app:https://github.com/docker/for-linux/files/3192118/main.c.zip
tcpdump capture: https://github.com/docker/for-linux/files/3192155/capture.pcap.zip