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Nikolay Chuprina's questions

Martin Hope
chupnik
Asked: 2023-07-19 22:06:04 +0800 CST
  • 6

Host: 192.168.1.144/24
VMs(routed) network: 192.168.122.0/24

I have VMs connected to libvirt's routed network.

<network>
  <name>routed-122</name>
  <uuid>86ca64a6-7fea-4cf8-9625-fa45fe944c2c</uuid>
  <forward mode='route'/>
  <bridge name='virbr1' zone='public' stp='on' delay='0'/>
  <mac address='52:54:00:0e:84:40'/>
  <domain name='routed_nat'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.128' end='192.168.122.254'/>
      <host mac='52:54:00:32:a9:9d' name='kvm-srv01' ip='192.168.122.131'/>
      <host mac='52:54:00:82:b7:f7' name='kvm-srv02' ip='192.168.122.132'/>
      <host mac='52:54:00:ee:38:54' name='kvm-srv03' ip='192.168.122.133'/>
    </dhcp>
  </ip>
</network>

UDP works successfully between:
VMs <--> bridge virbr1(192.168.122.1)
VMs <--> host external network (192.168.1.0/24)

UDP does not work between:
VMs <--> Host 192.168.1.144/24

At the same time, TCP works without problems!

I check the operation of UDP in this way (via iperf3 -u, which means UDP mode):

  1. on HOST: iperf3 -s (server mode)
  2. on VM: iperf3 -u -c HOST-IP
    Or vice versa - the result is the same, no communication via UDP.

The dump via Wireshark shows the following. enter image description here Tried connecting VMs via default NAT network (192.168.100.0/24) - same issue.
Ran into this while experimenting with docker swarm.

linux-networking