Probs With Routing (CentOS7 , KVM)

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Hi there, I’ve installed a new KVM-Server. The routing in all instances are only working after “arp -s ip_of_router mac_of_router”

Server: CentOS7, KVM
Clients: CentOS6 and Fedora 21

What going wrong?

[root@bgstkvmlr01 ~]# ifconfig bond0: flags=5187 mtu 1500
inet6 fe80::3ed9:2bff:fe0b:c706 prefixlen 64 scopeid 0x20 ether 3c:d9:2b:0b:c7:06 txqueuelen 0 (Ethernet)
RX packets 7341811 bytes 9977559369 (9.2 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2649574 bytes 3041071431 (2.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

br0: flags=4163 mtu 1500
inet 10.20.91.233 netmask 255.255.255.0 broadcast 10.20.91.255
inet6 fe80::3ed9:2bff:fe0b:c706 prefixlen 64 scopeid 0x20 ether 3c:d9:2b:0b:c7:06 txqueuelen 0 (Ethernet)
RX packets 502795 bytes 41156803 (39.2 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 404863 bytes 2871651286 (2.6 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

enp3s0f0: flags=6211 mtu 1500
ether 3c:d9:2b:0b:c7:06 txqueuelen 1000 (Ethernet)
RX packets 7318606 bytes 9975484026 (9.2 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2649122 bytes 3041013575 (2.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

enp3s0f1: flags=6211 mtu 1500
ether 3c:d9:2b:0b:c7:06 txqueuelen 1000 (Ethernet)
RX packets 23205 bytes 2075343 (1.9 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 452 bytes 57856 (56.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73 mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 0 (Lokale Schleife)
RX packets 587461 bytes 3015361475 (2.8 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 587461 bytes 3015361475 (2.8 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

virbr0: flags=4099 mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast
192.168.122.255
ether 52:54:00:04:a7:50 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

vnet0: flags=4163 mtu 1500
inet6 fe80::fc54:ff:fe63:59c4 prefixlen 64 scopeid 0x20 ether fe:54:00:63:59:c4 txqueuelen 500 (Ethernet)
RX packets 362 bytes 29416 (28.7 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3751 bytes 310945 (303.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

vnet1: flags=4163 mtu 1500
inet6 fe80::fc54:ff:fea4:7493 prefixlen 64 scopeid 0x20 ether fe:54:00:a4:74:93 txqueuelen 500 (Ethernet)
RX packets 594280 bytes 54135245 (51.6 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 6887388 bytes 9904127165 (9.2 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

[root@bgstkvmlr01 ~]# route -n
Kernel IP Routentabelle Ziel Router Genmask Flags Metric Ref Use Iface
0.0.0.0 10.20.91.1 0.0.0.0 UG 0 0 0
br0
10.20.91.0 0.0.0.0 255.255.255.0 U 0 0 0
br0
169.254.0.0 0.0.0.0 255.255.0.0 U 1011 0 0
br0
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0
virbr0
[root@bgstkvmlr01 ~]#

Mit freundlichen Gr

One thought on - Probs With Routing (CentOS7 , KVM)

  • Hi,

    Your report is not very clear. Is it just the routing from the guests that is not working? Because if you have to use that command, all routing from the server itself would also be jammed. And in that case, I
    would suggest doing a traffic capture on the bridge, bonding and its slaves if applicable to see where it’s breaking. You may also consider switching to bonding Active/Backup mode (if not already) for troubleshooting.

    Marcelo

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