On Fri, 17 Jan 2020 at 07:37, Asle Ommundsen <aommundsen at gmail.com> wrote: > > On Thu, 16 Jan 2020 15:34:43 +0100, Stephen John Smoogen > <smooge at gmail.com> wrote: > > > On Thu, 16 Jan 2020 at 07:58, Asle Ommundsen <aommundsen at gmail.com> > > wrote: > >> > >> Hi, > >> > >> Tonight I upgraded two CentOS 8 boxes to CentOS 8.1 (1911). Then after a > >> reboot of the first server the network was unavailable. In IPMI console > >> everything except the network was looking good. Network was unreachable. > >> No errors in NetworkManager. I also restarted NetworkManager, but it did > >> not help. Then I discovered that the default gateway suddenly was > >> missing. > >> > >> Then I rebooted the server one more time, but network was still down. > >> > >> Then both myself and a technician in my datcenter was debugging this (I > >> had to wake him up in the middle of the night, costing me a lot of > >> money), > >> without finding any reason for why the default gateway was missing after > >> reboot. > >> > >> Then we rebooted the server a third time, and all of a sudden the > >> problem > >> was gone and the default gateway was back. [...cut...] > > > In order to determine what is going on you need to give a lot more > > information. > > > > 1. How do these boxes get their network information? DHCP or static > > 2. If they are static, what controls the setting of ips: > > NetworkManager or network-scripts > > 3. If they are static, how are they set in > > /etc/sysconfig/network-scripts/ > > 4. Do the files in /etc/sysconfig/network-scripts list a GATEWAY= > > 5. If you are using network-manager, what does nmtui or the graphical > > tool say the gateway or default route is? > > Here is answers to your list. I have anonymized the some of the data: > Thank you for the detailed answers.. they eliminated most of the 'easy-to-fix' problems. If you do not have ipv6 you might want to turn that off as I have seen some problems where a router gives enough info to cause routing issues but shouldn't have. If you do have ipv6 and it works.. then never mind. The only other confused one i have seen is where eno1 and eno2 both have DEFROUTE=yes defined.. and you can't do that. Otherwise.. I am not sure and it will take going through the logs or repeating it happen to diagnose better. > 1) Static ip configuration > > 2) This should be NetworkManager. > nmcli output: > > eno1: connected to eno1 > inet4 1.1.1.234/29 > route4 1.1.1.232/29 > route4 0.0.0.0/0 > > eno2: connected to eno2 > inet4 192.168.0.5/24 > route4 192.168.0.0/24 > > [root at server ~]# nmcli d show | grep IP4.GATEWA > IP4.GATEWAY: 1.1.1.1.233 > > 3) > TYPE=Ethernet > PROXY_METHOD=none > BROWSER_ONLY=no > BOOTPROTO=none > DEFROUTE=yes > IPV4_FAILURE_FATAL=yes > IPV6INIT=yes > IPV6_AUTOCONF=yes > IPV6_DEFROUTE=yes > IPV6_FAILURE_FATAL=no > IPV6_ADDR_GEN_MODE=stable-privacy > NAME=eno1 > UUID=1f9ec889-3c64-470a-894b-05543ee44c29 > DEVICE=eno1 > ONBOOT=yes > IPADDR=1.1.1..234 > PREFIX=29 > GATEWAY=1.1.1.233 > IPV6_PRIVACY=no > > 4) Yes > > 5) > [root at server ~]# nmcli d show | grep IP4.GATEWA > IP4.GATEWAY: 1.1.1.233 > > nmtui shows the same gateway. > > Kind regards, > Asle Ommundsen > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos -- Stephen J Smoogen.