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msikscurloc
Enthusiast
Enthusiast

Multiple NICs / Multiple Default Gateways

I have a few VMs that have dual NICs (say NIC1 and NIC2).  Initially, in Windows, I'm only assigning a default gateway to NIC1.

In my IP Customizations (under Network Mapping) I have it setup to NOT assign a gateway to NIC2.  I left it blank.

However, after a test or failover, it still ends up assigning a gateway to NIC2.  And, because of this, Windows and my application get confused on which NIC to egress.

My current workaround is to assign NIC2 a higher metric. 

Has anyone else seen this problem?  This a bug or how it's intended to work?

Thanks in advance for your help!

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ashilkrishnan
VMware Employee
VMware Employee

Hi

If you do not customize a NIC on the recovery site, the NIC continues to use the IP settings from the protected site, and vice versa'

Please share these information:

1. What is the version of SRM ?

2. Have you configured IP customization just at protected site or for both sites

3.. Please share a screenshot of what configurations are selected and what are left blank

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msikscurloc
Enthusiast
Enthusiast

Thanks for the reply!

When our VMs fails over to the , they are in a different subnet.  So I do SRM to change it.

For the record, I'm using 8.3... but 8.2 also has this issue.

1. Current versions are the same at both sites:

SRM 8.3.0.2 (8.3.0.16356494)

VRA 8.3.0.2 (8.3.0.16284276)

2.  I configured IP customizations at both sites, both without a gateway defined. 

3. Screenshots:

2020-07-31_12-19-25.png

2020-07-31_12-25-17.png

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msikscurloc
Enthusiast
Enthusiast

So, it seems that 8.5.0 still has the same problem.  I did a complete reinstall of SRM too, thinking there may have been some leftovers.  However, it didn't seem to make any difference.  

I only want 1 of my NICs to be assigned a default gateway.  But no matter what I do, during a failover or test, it assigns one to both NICs.

Any ideas on how I can overcome this?  Thanks in advance!

vCenter 6.7.0.50000

SRM 8.5.0.18710000

VRA 8.5.0.18598070

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ib-dell
Contributor
Contributor

Hi,

I have a customer with the same issue, did you fix it?

Thank you

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msikscurloc
Enthusiast
Enthusiast

There has not been a fix supplied by VMware unfortunately, not that I've seen.  So to overcome this issue, I had to change the metric on the NIC that I don't want using its default gateway and give it a lower priority for routing.  It's not perfect, but it seemed to do the trick.

First, you need to run a "netstat -rn" to view your network adapters, their Mac addresses, and which index number(s) they've been assigned.

netstat.png

In this example, it's "Ethernet Adapter #2" that I don't want using its default gateway.  You will also notice the index number for that is 4.

The default metric is typically "16".   To increase it, thus giving it a lower priority, you run the following:

Set-NetIPInterface -InterfaceIndex 4 -InterfaceMetric 100

Now anytime you create any outgoing network traffic, it will use the interface with the lower metric (higher priority).

Hopefully, this helps some?

ib-dell
Contributor
Contributor

Hi,

thank you for your quick answer, really appreciated.

This is something more similar to a workaround, that is good, but not enough for us as a final solution. 

We are trying to contract the VMware support in order to have an official solution, if i will have it , i will update you on this thread.

thank you again

Ivan

 

 

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