问题：

[root@rac19c01 ~]# ip a
1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens33: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:73:28:16 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.61/24 brd 192.168.1.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::99e4:3fd5:dee8:ea21/64 scope link noprefixroute
       valid_lft forever preferred_lft forever
3: ens34: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:50:56:37:17:0d brd ff:ff:ff:ff:ff:ff
4: virbr0: mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:54:00:59:a5:44 brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
5: virbr0-nic: mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000
    link/ether 52:54:00:59:a5:44 brd ff:ff:ff:ff:ff:ff

修改配置文件后重启网络服务：

[root@rac19c01 ~]# ifconfig ens34 up

--重启未报错

--再次检查，依旧不生效

总结：ens34网段未生效，检查虚拟机网络配置和相关windows的网络配置，均显示正常

解决

后找人询问后发现是因为配置文件书写错误

正确如下：

[root@rac19c01 ~]# vi /etc/sysconfig/network-scripts/ifcfg-ens34
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens34
UUID=30760386-ffe4-4245-b3b4-47710c316c54
DEVICE=ens34
ONBOOT=yes    #此处onboot需设置成yes，设置成开机自启动
IPADDR=192.168.2.61
PREFIX=24
#GATEWAY=192.168.2.1   #此处网关设置需要注释掉，否则ip不生效
IPV6_PRIVACY=no

随机重启网络服务：

[root@rac19c01 ~]# service network restart
Restarting network (via systemctl):                        [  OK  ]

--网络服务重启正常

--再次检查，发现ip生效，ens34启动成功
 

[root@rac19c01 ~]# ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::1/128 scope hostvalid_lft forever preferred_lft forever
2: ens33:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000link/ether 00:0c:29:73:28:16 brd ff:ff:ff:ff:ff:ffinet 192.168.1.61/24 brd 192.168.1.255 scope global noprefixroute ens33valid_lft forever preferred_lft foreverinet6 fe80::99e4:3fd5:dee8:ea21/64 scope link noprefixroutevalid_lft forever preferred_lft forever
3: ens34:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000link/ether 00:50:56:37:17:0d brd ff:ff:ff:ff:ff:ffinet 192.168.2.61/24 brd 192.168.2.255 scope global noprefixroute ens34valid_lft forever preferred_lft foreverinet6 fe80::63d2:b0ff:a37c:c981/64 scope link noprefixroutevalid_lft forever preferred_lft forever
4: virbr0:  mtu 1500 qdisc noqueue state DOWN group default qlen 1000link/ether 52:54:00:59:a5:44 brd ff:ff:ff:ff:ff:ffinet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0valid_lft forever preferred_lft forever
5: virbr0-nic:  mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000link/ether 52:54:00:59:a5:44 brd ff:ff:ff:ff:ff:ff
[root@rac19c01 ~]#