Docker networking

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docker networks

Overview

On a docker swarm

heth@docker1:~$ docker network ls
NETWORK ID     NAME              DRIVER    SCOPE
76a4537b0654   bridge            bridge    local
d6ae77b0b494   docker_gwbridge   bridge    local
cc493462394a   host              host      local
p3lm08ns2mrq   ingress           overlay   swarm
ba8252e136b1   none              null      local

on each node in swarm run:

heth@docker1:~$ docker network inspect ingress | grep Address
                "MacAddress": "02:42:0a:00:00:02",
                "IPv4Address": "10.0.0.2/24",
                "IPv6Address": ""
heth@docker3:~$docker network inspect ingress | grep Address
                "MacAddress": "02:42:0a:00:00:03",
                "IPv4Address": "10.0.0.3/24",
                "IPv6Address": ""
heth@docker3:~$ docker network inspect ingress | grep Address
                "MacAddress": "02:42:0a:00:00:04",
                "IPv4Address": "10.0.0.4/24",
                "IPv6Address": ""

Creating an overlay network

heth@docker1:~$docker network create --driver overlay hethnet

Run containers on swarm

heth@docker1:~$docker service create --replicas 3 --network hethnet --name helloworld alpine ping docker.com
heth@docker1:~$ docker service ps helloworld
ID             NAME           IMAGE           NODE      DESIRED STATE   CURRENT STATE            ERROR     PORTS
3lgo2gz3a4yb   helloworld.1   alpine:latest   docker2   Running         Running 24 minutes ago
u6e8agzh22az   helloworld.2   alpine:latest   docker3   Running         Running 24 minutes ago
9ix7pu6m9hpf   helloworld.3   alpine:latest   docker1   Running         Running 24 minutes ago

Create traffic between nodes

heth@docker1:~$ docker exec -it 1f sh
/ # ip a
31: eth0@if32: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1450 qdisc noqueue state UP
    link/ether 02:42:0a:00:01:03 brd ff:ff:ff:ff:ff:ff
    inet 10.0.1.3/24 brd 10.0.1.255 scope global eth0
       valid_lft forever preferred_lft forever
/ # ping 10.0.1.5
PING 10.0.1.5 (10.0.1.5): 56 data bytes
64 bytes from 10.0.1.5: seq=0 ttl=64 time=0.338 ms
64 bytes from 10.0.1.5: seq=1 ttl=64 time=0.270 ms
...

On another terminal start tcpdump while ping still running

root@docker1:/home/heth# sudo tcpdump -i ens160 -w /tmp/swarm.pcap

Transfer swarm.pcap to host with wireshark and notice VxLAN tunneling Vxlan tunneling.png

Bridged interfaces

Example

brctl command

Install with (debian like): sudo apt install bridge-utils

heth@ub1:~$ brctl show
bridge name     bridge id               STP enabled     interfaces
br-501d0044fabe         8000.0242a9d6ae8d       no              veth413579c
                                                        veth6d6fce4
                                                        vethd3cbce2
br-ded1f2526def         8000.0242a675d928       no
crc             8000.525400fdbed0       yes
docker0         8000.02420af91289       no              veth180ce2d
virbr0          8000.5254009d12fa       yes
heth@ub1:~$ brctl showmacs br-501d0044fabe
port no mac addr                is local?       ageing timer
  1     02:42:ac:13:00:02       no                 3.96
  2     02:42:ac:13:00:03       no                 3.96
  1     46:b0:4b:02:26:99       yes                0.00
  1     46:b0:4b:02:26:99       yes                0.00
  2     96:fb:5a:ff:2c:9d       yes                0.00
  2     96:fb:5a:ff:2c:9d       yes                0.00
  3     aa:2c:8a:2b:06:81       yes                0.00
  3     aa:2c:8a:2b:06:81       yes                0.00

bridge command

heth@ub1:~$ bridge -d  vlan
port              vlan-id
virbr0            1 PVID Egress Untagged
                    state forwarding
crc               1 PVID Egress Untagged
                    state forwarding
docker0           1 PVID Egress Untagged
                    state forwarding
br-ded1f2526def   1 PVID Egress Untagged
                    state forwarding
veth180ce2d       1 PVID Egress Untagged
                    state forwarding
br-501d0044fabe   1 PVID Egress Untagged
                    state forwarding
veth413579c       1 PVID Egress Untagged
                    state forwarding
vethd3cbce2       1 PVID Egress Untagged
                    state forwarding
veth6d6fce4       1 PVID Egress Untagged
                    state forwarding

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