Occasional ping issues over IPv6

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1

Docker version 24.0.9, build 2936816

I use docker with v6 now some time with no obvious issues so far. Well, I migrated one CheckMK instance to docker and since then CMK detects packet loss. I also can observe, that ping command reports the same for v6 pings:

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I can reproduce this with any container (here tested with ubuntu:22.04 with iputils-ping).

Is this a docker issue or a setup issue?

The Modem/Router is IPv6 enabled and I get a prefix. I run the containers with a macvtap interface and assign an own MAC with --mac-address. inspect of the network interface in use:

docker network inspect eth0
[
    {
        "Name": "eth0",
        "Id": "79a5ad4cb3824a386fe9369cfd584a9b2e2e44c6be3807074ca05fc54d23bdbb",
        "Created": "2024-01-27T14:53:49.585738367+01:00",
        "Scope": "local",
        "Driver": "macvlan",
        "EnableIPv6": true,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "192.168.178.0/24",
                    "Gateway": "192.168.178.1",
                    "AuxiliaryAddresses": {
                        "server": "192.168.178.3"
                    }
                },
                {
                    "Subnet": "xxxx::/64",
                    "Gateway": "xxxx::1",
                    "AuxiliaryAddresses": {
                        "server6": "xxxx:fe22:2f7c"
                    }
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
        },
        "Options": {
            "parent": "vhost0"
        },
        "Labels": {}
    }
]

Also tested with docker on a different linux host.

Any ideas whats wrong or how I could diagnose this?

1 Like
2

Some updates.

My test cases:

occasional ping6 issues with:

docker run -it \
  --rm \
  --net='eth0' \
  --ip='192.168.178.202'
  'ubuntu:22.04' /bin/bash

and NO issues with bridge:

docker run -it \
  --rm \
  --net='bridge' \
  'ubuntu:22.04' /bin/bash

(dont forget to apt update && apt install inetutils-ping).

Bith times ping6 google.com was executed

Any idea why the eth0 interface is causing those issues?