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/ipv6 address ping across availability zone not working/

ipv6 address ping across availability zone not working


We have created a VPC and enabled the ipv6 CIDR. We have created 2 subnets one in each AZ. Created the ipv6 cidr and auto assign is also enabled.

Security group is created and with ICMP6 to be available for ::0/ traffic. Also within the same security group all traffic is enabled.

We created 2 EC2 instances one in each AZ and checked from within the OS both are getting the ipv6 address assigned .

We added a route like below in both the EC2 instances. ip -6 r a <IPv6-VPC-CIDR> dev eth0 proto kernel metric 256 pref medium

Now when we try to ping ipv4 address from each other instance it works fine. but when we try to ping ipv6 address it does not work. No output is there.

kindly let us know if we are missing anything here.

1 Answers

I just set up two new instances in IPv6-enabled subnets with security groups as you describe using Amazon Linux 2. I can ping (IPv4) and ping6 (IPv6) between the instances without any issues. I can also SSH using their IPv4 and IPv6 addresses.

I didn't have to add any routes to the instances - it just worked out of the box so I'd suggest not doing that if you don't have to.

You also haven't specific the OS type so it's difficult to figure out what else to suggest.

So, try this: Create a new VPC; new IPv4 and IPv6 CIDR ranges; two new subnets; then launch your instances.

answered 5 months ago
  • Thanks for the response. Well if you check the instance would be using Network Manager and not the cloud-init.

    systemctl status NetworkManager

    The issue with NetworkManager is if we attach a second interface to the EC2 instance, that does not get configured inside the VM. so to avoid the manual configuration/routing for the secondary interface, we use cloud-init and it works fine. but with cloud-init ipv6 is not pingable across the AZ.

    Also, kindly share the AMI that you used. we are using the centOS 7.9 image with cloud-init as cloud-init-19.4-7.el7.centos.5.x86_64

  • I used the default Amazon Linux 2 AMI on an ARM instance. For testing, i would encourage you to start simple: one ENI and see how it goes; then attach a second interface once you get things working.

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