In my server, I have 2 public interfaces with 2 public IPs and 1 has private IP too.
eno1 - 149.20.185.126 (public), 10.2.2.2 (private)
eno2 - 149.20.185.54 (public)
For some other work (DPDK bind) I need to down the eno1 interface for some time and then up again. Then I found out that even a normal ifconfig restart caused network issues.
I did ssh connect via 149.20.185.154(eno2) and then restart ("ifconfig eno1 down" & "ifconfig eno1 up") the eno1 interface. Sometimes the IP 149.20.185.126(eno1) immediately gets responding but sometimes not (I kept doing ping from other servers to check). Sometimes this IP gets unavailable after even 20-30 minutes of interface restart and again gets available. Whenever it gets unavailable after interface restart I tried restarting networking services but same but the IP doesn't get online immediately. Though server reboot solves all the problems, I want to avoid this.
I also checked routing table and it's the same after interface restart so it isn't causing problem for sure..! As I was told Cent OS is not showing this issue. Is this Ubuntu issue or I am doing something wrong while restarting interface?
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 149.20.185.1 0.0.0.0 UG 0 0 0 eno2
0.0.0.0 149.20.185.1 0.0.0.0 UG 0 0 0 eno1
10.2.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eno1
149.20.185.0 0.0.0.0 255.255.255.128 U 0 0 0 eno2
149.20.185.0 0.0.0.0 255.255.255.128 U 0 0 0 eno1
default via 149.20.185.1 dev eno2 proto static
default via 149.20.185.1 dev eno1 proto static
10.2.2.0/24 dev eno1 proto kernel scope link src 10.2.2.2
149.20.185.0/25 dev eno2 proto kernel scope link src 149.20.185.54
149.20.185.0/25 dev eno1 proto kernel scope link src 149.20.185.126
