By default dhcpd based network bridge configured by libvirtd. You can verify that with the following commands:

# brctl show
# virsh net-list

KVM default networking All VMs (guest machine) only have network access to other VMs on the same server. A private network 192.168.122.0/24 created for you. Verify it:

# virsh net-dumpxml default

If you want your VMs avilable to other servers on your LAN, setup a a network bridge on the server that connected to the your LAN.

Update your nic config file such as ifcfg-enp3s0 or em1: # vi /etc/sysconfig/network-scripts/enp3s0

Add line:

BRIDGE=br0

Save and close the file in vi. Edit /etc/sysconfig/network-scripts/ifcfg-br0 and add:

# vi /etc/sysconfig/network-scripts/ifcfg-br0

Append the following:

DEVICE="br0"
# I am getting ip from DHCP server #
BOOTPROTO="dhcp"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
ONBOOT="yes"
TYPE="Bridge"
DELAY="0"

Restart the networking service (warning ssh command will disconnect, it is better to reboot the box):

# systemctl restart NetworkManager

Verify it with brctl command:

# brctl show

By KVM Virtual Manager can be created bridge interface on each of network interface

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-br1
DEVICE="br1"
ONBOOT="yes"
TYPE="Bridge"
BOOTPROTO="none"
IPADDR="10.5.22.51"
NETMASK="255.255.255.0"
GATEWAY="10.5.22.254"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
DHCPV6C="no"
STP="on"
DELAY="0.0"

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-br2
DEVICE="br2"
ONBOOT="yes"
TYPE="Bridge"
BOOTPROTO="none"
IPADDR="10.5.23.10"
NETMASK="255.255.255.0"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
DHCPV6C="no"
STP="on"
DELAY="0.0"

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BRIDGE="br1"

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
ONBOOT=yes
BRIDGE="br2"

[root@localhost ~]# cat /sbin/ifup-local
#!/bin/sh
 
ip route add default via 10.5.23.254 dev br2 table rt2;
ip rule add from 10.5.23.0/24 table rt2