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Question
Friday, November 2, 2018 3:39 AM
We have a 2012Rs Server that is dual homed (2 network interfaces)
Lets say
NIC-A has IP address 192.168.1.1/24
NIC-B has IP address 192.168.2.1/24
Both interfaces connect to a the same router (CISCO) on different interfaces in the router
so the router has
INTERFACE Gi0/1 192.168.1.96/24
INTERFACE Gi0/2 192.168.2.96/24
We have an application running on the server that can only support 1 interface (it is configured to use NIC-B) and have need for workstations on 192.168.1.0/24 to access the application, but they must do it by connecting to 192.168.2.1.
This appears to not work (we have the application on a Server 2008R2 and it is working, but want to upgrade off 2008R2)
This seems to be a reverse path issue, and we had the same scenario when we upgraded our CENTOS servers from 5.x to 7.x.
The solution in CENTOS is edit /etc/sysctl.conf and change
set net.ipv4.conf.all.rp_filter = 0
Is there a way to do the same thing on a Windows Server 2012R2 and beyond?
All replies (3)
Thursday, November 8, 2018 2:13 PM
Hello SD Werner,
Thank you for your question.
This should be to see if your router supports this feature. It is recommended that you go to the Cisco website to see if your router has the relevant technology by entering your router version and model.
Best Regards,
Leon
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Thursday, November 8, 2018 2:20 PM
Hi,
I believe if you change the interface metric you can achieve.
Thanks
Syed
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Thursday, February 14, 2019 1:44 PM
Hi,
I don't know if you have fixed this issue or not but I would like to post the possible solution to the problem.
I have encountered the exact same issue on a Windows Server 2016 machine.
The behavior you have described is known as asymmetric routing/traffic. Starting from Windows Server 2008 R2, the Next Generation TCP/IP stack supports strong host sends and receives for both IPv4 and IPv6 by default on all interfaces except the Teredo tunneling interface for a Teredo host-specific relay. You can find more details here regarding strong host send and receive here: https://docs.microsoft.com/en-us/previous-versions/technet-magazine/cc137807(v=msdn.10)
In order to disable the default behavior you need to issue the commands below for NIC-A and NIC-B:
netsh interface ipv4 set interface NIC-A weakhostsend=enabled
netsh interface ipv4 set interface NIC-B weakhostsend=enabled
netsh interface ipv4 set interface NIC-A weakhostreceive=enabled
netsh interface ipv4 set interface NIC-B weakhostreceive=enabled
Other resources mentioning the correct solution:
https://superuser.com/questions/1178128/asymmetric-ping-between-two-windows-7-hosts
https://eaglebcr.wordpress.com/2012/07/24/strong-vs-weak-host-model/
Thank you,