[lxc-users] lxc container network occasional problem with bridge network on bonding device

[Andrey Repin]

Greetings, toshinao!

> Hi.

> I experienced occasional network problem of containers running on ubuntu server 18.04.1. Containers
> can communicate with host IP always and they can communicate sometimes to the other hosts but they
> are disconnected occasionally. When the problem occurs, the ping from the container to external hosts
> does not reach at all, but very rarely they recover after, for example, several hours later.
> Disconnection happens much more easily. 

> The host network is organized by using netplan in the following topology.

>            +-eno1-< <--lan_cable--> >-+
> br0--bond0-+                          +-- Cisco 3650
>            +-en02-< <--lan_cable--> >-+

> The bonding mode is balance-a1b.

ALB
Adaptive Load Balancing

> I also found that if one of the LAN cables is physically disconnected,
> this problem has never happened.

How do you connect containers to the bridge?

> By using iptraf-ng, I watched the bridge device, the following br0, as well as the slave devices.
> Even if containers send a ping to the external hosts, no ping packet is detected, when they cannot
> communicate. Ping packets are detected by iptraf-ng on these devices when the communication is working.

> I guess this can be a low-level problem of virtual networking. Are there any suggestions to solve
> the problem ?

Can containers talk to each other when this happens?
Can host talk to the world at that same time?

> Here's the detail of the setting.

> host's netplan setting

> network:
> version: 2
> renderer: networkd
> ethernets:
>   eno1:
>     dhcp4: no
>   eno2:
>     dhcp4: no
> bonds:
>   bond0:
>     interfaces: [eno1, eno2]
>     parameters:
>       mode: balanec-a1b

And netplan did not yell at you?

> bridges:
>   br0:
>     interfaces:
>       - bond0
>     addresses: [10.1.2.3/24]
>     gateway4: 10.1.2.254
>     dhcp4: no

> host network interface status

> host# ip a s
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
>    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>    inet 127.0.0.1/8 scope host lo
>       valid_lft forever preferred_lft forever
>    inet6 ::1/128 scope host
>       valid_lft forever preferred_lft forever
> 2: eno1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master
> bond0 state UP group default qlen 1000
>    link/ether 0b:25:b5:f2:e1:34 brd ff:ff:ff:ff:ff:ff
> 3: eno2: <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP> mtu 1500 qdisc mq master
> bond0 state UP group default qlen 1000
>    link/ether 0b:25:b5:f2:e1:35 brd ff:ff:ff:ff:ff:ff
> 4: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
>    link/ether 0a:1a:6c:85:ff:ed brd ff:ff:ff:ff:ff:ff
>    inet 10.1.2.3/24 brd 10.1.2.255 scope global br0
>       valid_lft forever preferred_lft forever
>    inet6 fe80::81a:6cff:fe85:ffed/64 scope link
>       valid_lft forever preferred_lft forever
> 5: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue
> master br0 state UP group default qlen 1000
>    link/ether 0a:54:4b:f2:d7:10 brd ff:ff:ff:ff:ff:ff
> 7: vethK4HOFU at if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
> master br0 state UP group default qlen 1000
>    link/ether fe:ca:07:3e:2b:2d brd ff:ff:ff:ff:ff:ff link-netnsid 0
>    inet6 fe80::fcca:7ff:fe3e:2b2d/64 scope link
>       valid_lft forever preferred_lft forever
> 9: veth77HJ0V at if8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
> master br0 state UP group default qlen 1000
>    link/ether fe:85:f0:ef:78:b2 brd ff:ff:ff:ff:ff:ff link-netnsid 1
>    inet6 fe80::fc85:f0ff:feef:78b2/64 scope link
>       valid_lft forever preferred_lft forever

> container's network interface status

> root at bionic0:~# ip a s
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
>    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>    inet 127.0.0.1/8 scope host lo
>       valid_lft forever preferred_lft forever
>    inet6 ::1/128 scope host
>       valid_lft forever preferred_lft forever
> 6: eth0 at if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
>    link/ether 00:16:3e:cb:ef:ce brd ff:ff:ff:ff:ff:ff link-netnsid 0
>    inet 10.1.2.20/24 brd 10.1.2.255 scope global eth0
>       valid_lft forever preferred_lft forever
>    inet6 fe80::216:3eff:fecb:efce/64 scope link
>       valid_lft forever preferred_lft forever


-- 
With best regards,
Andrey Repin
Monday, September 17, 2018 20:41:41

Sorry for my terrible english...