the important bit there is: > 3. We should have the installer sanity-check this if we can > (That the node-config.yaml mtu value is less than the default > route's MTU.)
https://github.com/openshift/openshift-ansible/pull/815 The simplest test is to set the mtu on the default interface (eth0 on my host) to something other than 1500 ('ip link set dev eth0 1400' for example), and then run the playbooks/byo/openshift_facts.yml playbook. The value of openshift.node.sdn_mtu should be a string representing the set mtu value - 50 A full config run should yield a node-config.yaml that has networkConfig.mtu set to the same value above. If the inventory does not specify openshift_ip for the host, then the mtu detection is done using the auto-detected value of openshift.common.ip to try to find the correct interface. If the inventory specifies an override for openshift_ip, then the mtu detection will attempt to find the interface associated with that ip.
Verified this bug with PR#815, and PASS. On all the nodes in the cluster, run the following command: # ip link set dev eth0 mtu 1400 # ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1400 inet 192.168.0.107 netmask 255.255.255.0 broadcast 192.168.0.255 inet6 fe80::f816:3eff:fede:f1be prefixlen 64 scopeid 0x20<link> ether fa:16:3e:de:f1:be txqueuelen 1000 (Ethernet) RX packets 199426 bytes 103284477 (98.4 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 164992 bytes 44501748 (42.4 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 Run ansible installation: $ cd openshift-ansible $ git checkout -b bz1277592 $ git pull https://github.com/detiber/openshift-ansible fixMTU After installation is done, go to all the nodes, check mtu setting. # grep mtu /etc/origin/node/node-config.yaml mtu: 1350 Install docker-registry. New app, trigger build, docker push successfully when data is sending across nodes.