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

[Tomasz Chmielewski]

FYI I've seen a similar phenomenon when launching new containers.

Sometimes, connectivity freezes for several seconds after that.

What usually "helps" is sending an arping to the gateway IP from an 
affected container.


Tomasz


On 2018-09-17 06:02, toshinao wrote:
> 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. I also found that if one of the LAN
> cables is physically disconnected,
> this problem has never happened.
> 
> 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 ?
> 
> 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
> 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
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