[openstack-dev] [Neutron][IPv6] Blueprint Bind dnsmasq in qrouter- namespace

Randy Tuttle randy.m.tuttle at gmail.com
Thu Dec 19 13:01:43 UTC 2013

First, dnsmasq is not being "moved". Instead, it's a different instance for the attached subnet in the qrouter namespace. If it's not in the qrouter namespace, the default gateway (the local router interface) will be the interface of qdhcp namespace interface. That will cause blackhole for traffic from VM. As you know, routing tables and NAT all occur in qrouter namespace. So we want the RA to contain the local interface as default gateway in qrouter namespace


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On Dec 19, 2013, at 4:05 AM, Xuhan Peng <pengxuhan at gmail.com> wrote:

> I am reading through the blueprint created by Randy to bind dnsmasq into qrouter- namespace:
> https://blueprints.launchpad.net/neutron/+spec/dnsmasq-bind-into-qrouter-namespace
> I don't think I can follow the reason that we need to change the namespace which contains dnsmasq process and the device it listens to from qdhcp- to qrouter-. Why the original namespace design conflicts with the Router Advertisement sending from dnsmasq for SLAAC?
> From the attached POC result link, the reason is stated as:
> "Even if the dnsmasq process could send Router Advertisement, the default gateway would bind to its own link-local address in the qdhcp- namespace. As a result, traffic leaving tenant network will be drawn to DHCP interface, instead of gateway port on router. That is not desirable! "
> Can Randy or Shixiong explain this more? Thanks!
> Xuhan 
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