yahoo-eng-team team mailing list archive

[Peter Slovak <peter.slovak@xxxxxxxxxxxxx>]

Public bug reported:

Currently, the "Attach Interface" button in dashboard always creates and
attaches a new interface, no matter whether the instance already has an
interface attached from a given subnet.

However, from the networking/routing standpoint, it doesn't make sense
to have a VM connected to the same subnet via two different "physical"
interfaces (eth0 and eth1 for example) - this makes the second and all
the subsequent IPs from that subnet unreachable unless you set up
source-based routing (inside the VM).

So, instead of creating a new Neutron port for each fixed IP, it might
be better to update an existing port in that subnet, if one has already
been attached to the instance. This is compatible with the Unix view of
more IPs in one subnet - they work on the same base MAC address and
cooperate with DHCP nicely. Moreover, such aliases don't confuse the
routing table and these IPs work "out of the box".

** Affects: horizon
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1568809

Title:
  Add new fixed IP to existing Neutron port, if one is attached

Status in OpenStack Dashboard (Horizon):
  New

Bug description:
  Currently, the "Attach Interface" button in dashboard always creates
  and attaches a new interface, no matter whether the instance already
  has an interface attached from a given subnet.

  However, from the networking/routing standpoint, it doesn't make sense
  to have a VM connected to the same subnet via two different "physical"
  interfaces (eth0 and eth1 for example) - this makes the second and all
  the subsequent IPs from that subnet unreachable unless you set up
  source-based routing (inside the VM).

  So, instead of creating a new Neutron port for each fixed IP, it might
  be better to update an existing port in that subnet, if one has
  already been attached to the instance. This is compatible with the
  Unix view of more IPs in one subnet - they work on the same base MAC
  address and cooperate with DHCP nicely. Moreover, such aliases don't
  confuse the routing table and these IPs work "out of the box".

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