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uberrebu
Asked: 2017-08-22 19:14:08 +0800 CST

asymmetric routing for ENI for routing traffic for ELB

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I have been able to setup 2 ENI to work on ec2 RHEL instances (ip routing for extra eni on RHEL ec2 instances)

but now i have application using the eth1 for inter-cluster communication and services are bind to the eth1

but the problem is ELB routes to eth0 by default

does anyone know how to edit my routes here (ip routing for extra eni on RHEL ec2 instances) to allow ELB to route traffic to eth1?

Thanks

Default:

ELB ==> eth0 (nothing is bounded here)

what i want:

ELB ==> eth1

OR

ELB ==> eth0 ==> eth1
networking

1 Answers

  1. Many people have now questioned why it is necessary to have two network interfaces on the same subnet. The only information you have given us to go on is that you "need a static eni."

    All I can do is assume you want a static IP address on an interface, and you failed to configure the primary interface the proper way when creating the instance.

    You will not find any documentation in AWS to support your request, because it is not supported and should not be done.

    In fact, here is the exact wording under best practices in the ENI configuration guide:

    If you attach two or more network interfaces from the same subnet to an instance, you may encounter networking issues such as asymmetric routing. If possible, use a secondary private IPv4 address on the primary network interface instead. For more information, see Assigning a Secondary Private IPv4 Address.

    If your problem is that you configured the first interface wrong, then add additional IP addresses to the primary interface. Or, better yet, simply create an AMI of the server, and redeploy a new server with the proper network interface settings. The whole process takes less than 15 minutes.

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