2009/200 Solaris Simlinks

[James Carlson]

I'm sponsoring this fast-track request for Rishi Srivatsavai.  The
timer is set to 04/02/2009.


This project introduces simlinks  with stability level of Uncommitted,
the private data-link properties  for simlinks are Project Private and
the release binding is Minor.


Simulated links (simlinks) are pseudo  GLDv3 network devices that aid in
the  creation of  point-to-point network  links  on a  system. They  are
intended to be  a testing resource for  OpenSolaris developers. Simlinks
should help in developing test suites that can run  with minimal network
hardware  and test  protocols  and codepaths  that  were previously  not
possible to test  on a single system. This case  has two components: the
new  'simlink' pseudo  GLDv3 network  device driver  and the  changes in
dladm(1M) to  create, modify and  delete simlinks. The name  simlink was
chosen even  though it might be  confused with symlink, as  the name was
short and can be easily identified as a testing resource.

Simlinks are created  by the administrator on a  system using dladm(1M).
Simlinks can be of  type: Ethernet or WiFi and the  type is specified at
the time  of creation. When  creating a  new simlink device  the simlink
driver  uses  a  random  MAC  address and  registers  the  device  as  a
new  MAC  on the  system.  Once  created  administrators can  plumb  IP,
snoop  and create  VLANs  using the  new simlink.  In  other words  upon
creation  simlinks appear  as  regular  Ethernet/WiFi hardware  devices.
Simlink instances  persist and survive  reboot, unless created  with the
"temporary" option.

Initially new simlink devices have no peer link attached. No packets are
received  from  the device  and  all  packets  sent  to the  device  are
silently discarded.  In this  configuration simlinks  are of  limited to
no  use. Simlinks  must  have  another simlink  attached  to simulate  a
point-to-point link.  In such a  configuration packets transmitted  on a
simlink are received  at the other simlink and  vice-versa, simulating a
full-duplex point-to-point link.  Using a combination of  such links one
can simulate a number of  network configurations within a single system.
The point-to-point nature of the device allows us to write test software
that can  send and  capture packets  at both  the end-points  and verify
network software without  the distractions that arise from  the need and
the use of actual network hardware.

Simlinks  are  different  from  VNICs. Simlinks  are  used  to  simulate
point-to-point links and are MAC-level  objects that appear to consumers
as real Ethernet/WiFi devices. Therefore,  you may create an aggregation
on top of a  collection of simlinks, while such a  thing is not possible
with VNICs or the existing  Etherstubs. Such a configuration would allow
the testing of  aggregations (and LACP signaling) without  having to set
up multiple  physical point-to-point connections between  two systems. A
VNIC on  the other hand is  created over an Etherstub  or other existing
MAC-level objects  (such as  simlinks) to  provide bandwidth  control of
traffic on  the underlying  link. Etherstubs do  not have  MAC addresses
associated with them and are not suitable to simulate a single link.

The following dladm sub-commands are introduced by this case:

    create-simlink [-t] [-m <media>] <link>
	A new simlink device is created on the system with the given
	linkname. Media can either be Ethernet (default) or WiFi.
    modify-simlink [-t] [-p <peer>] <link>
	Another simlink is associated as the peer link of an existing
	simlink. If the -p option is not specified any existing peer
	link associated with the simlink instance is removed.
    delete-simlink [-t] <link>
	Delete simlink instance from the system. If the simlink has
	a peer simlink associated with it the command fails.
    show-simlink   [-pP] [-o <field>,...] [<link>]
	Lists the existing simlinks or when linkname is specified displays
	the given simlink on the system. Output fields are: LINK, MEDIA,
	MACADDRESS and OTHERLINK

Simlink instances  are of  data-link class  'DATALINK_CLASS_SIMLINK' and
the output from  'dladm show-link' lists simlink  instances as belonging
to class 'simlink'.  'dladm show-link' shows the simlink  peer (if there
is  one) in  the 'OVER'  field. Simlink  instances are  not included  in
the  output of  'dladm  show-phys'. Create,  modify  and delete  simlink
operations require sys_net_config privilege.

Simlinks are expected to be used during network software development and
testing on  OpenSolaris. To encourage  use of simlinks for  testing this
case proposes  project teams introduce new  private data-link properties
in  the simlink  driver that  modify or  control the  response from  the
device to administrative action.

For example to simulate a WiFi  scan the simlink driver introduces a new
_wl_esslist private  property. Before performing  a WiFi scan on  a WiFi
simlink, the _wl_esslist property of  the device can be initialized with
test values. Performing the WiFi scan on the simlink will return results
using  the values  set in  _wl_esslist property.  This case  proposes to
introduce the following two private properties with a stability level of
Project  Private and  are  listed  below as  examples.  As the  intended
usage  is with  testing  scripts  the stability  level  for the  private
properties shouldn't be a problem. A future project might introduce more
interactive APIs in addition to or in place of the proposed properties.

	_wl_esslist	WiFi scan results. Comma separated essid and
			signal stength pair to set a WiFi scan result.
			This property can be set multiple times (max 10)
			for multiple WiFi scan results.
	_wl_connected	Toggle to indicate the device is connected
			to a WiFi access point.

Wifi apsects of simlinks are intended for use by the NWAM team. Simlinks
are currently in use by the RBridges team to test bridging and the TRILL
protocol. As simlinks  appear as MAC-level objects they can  be used for
bridging. Using several point-to-point simlinks testing multiple bridged
LANs running the TRILL protocol can be done on a single box.

                    -----------                     ------------
   <red0>---<red1> | RBridge 1 | <blue0>---<blue1> | Rbridge 2 | ....
                    -----------                     ------------

   red0 and red1, blue0 and blue1 are simlinks.