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DHCP not providing IPv6 address to VM

asked 2017-07-21 11:05:17 -0500

Elangovan Anganann gravatar image

updated 2017-07-21 11:50:33 -0500

OpenStack Environment Details: I have an Ocata OpenStack HA environment (3 controllers, 2 compute). There are two NICs in each node: one private network and one public network. Private network is used for openstack inter-node communication. Public network is used for API access. All the NICs have IPv4 addresses (no IPv6 addresses configured as OpenStack disables IPv6 on Linux Bridges in the OS). Both private and public networks are FLAT networks (No VLANs).

Issue: I created a provider network (linux bridge driver) on the public network with two subnets: IPv4 subnet and IPv6 subnet (IPv6 Address mode: dhcpv6-stateful, IPv6 RA mode: dhcpv6 stateful). When I created a VM, OpenStack assigned IPv4 and IPv6 addresses. These addresses were visible in "openstack server list" command output.

But inside the VM, I could see only IPv4 address; I don't see IPv6 address. When I did tcpdump to track the DHCP communication between VM and controllers, I saw only IPv4 addresses getting offered to the VM. IPv6 addresses were not offered. I want the VM to get both IPv4 and IPv6 addresses.

How to achieve this?

Update: I delete IPv4 subnet and allowed the network with only IPv6 subnet. When I created a VM on this network, tcpdump show DHCP discover is broadcasted and these discover packets reached controller nodes. But DHCP didn't respond. Why this behavior?

[root@controller1 ~]# rpm -qa | grep dnsmasq
dnsmasq-2.66-21.el7.x86_64
dnsmasq-utils-2.66-21.el7.x86_64
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Comments

This article describes tenant ipv6 deployment with good example commands and explanations for the different options. It is from 2015 but still helpful.

http://www.debug-all.com/?p=52

luowei gravatar imageluowei ( 2017-07-21 12:06:23 -0500 )edit

Iuowei, That reference article using Openvswitch (NOT Linux Bridge).

Elangovan Anganann gravatar imageElangovan Anganann ( 2017-07-22 03:37:28 -0500 )edit

@Elangovan Anganann : Facing the same issue. I cant assign it manually and ping but DHCPv6 assigns IP addresses of subnet /128 hence I am unable to ping other VMs with IPv6.

AB239 gravatar imageAB239 ( 2018-03-07 00:17:46 -0500 )edit

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answered 2017-09-20 09:25:31 -0500

Eyepv6 gravatar image

Did you modify the interface settings in your VM to support DHCPv6? By default, many OSes will support SLAAC but not DHCPv6.

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Asked: 2017-07-21 11:05:17 -0500

Seen: 518 times

Last updated: Sep 20 '17