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lucet

Lucet compiler has to “compile” the wiring connections needed for a OpenFlow-SDN distributed machine. The "compilation" happens on two levels:

  • the topology representation in Dobby,
  • configuration files for Xen and LINCX.

Table of Contents

Configuration

System configuration file

Lucet has the following options that can be adjusted in the sys.config:

Parameter Description Example
dobby_node Erlang node name that runs Dobby '[email protected]'

Building and running

To build and run Lucet invoke make && make run.

API

Wiring identifiers in Dobby

lucet:wire(SrcId, DstId)

Creates bound_to path between SrcId and DstId in Dobby. SrcId and DstId are binaries for identifiers' names.

If SrcId or the path doesn't exist an error is returned.

A bound_to path can only consist of:

  1. OpenFlow Port identifiers (lm_of_port),
  2. Virtual Port identifiers (lm_vp),
  3. Physical Port identifiers (lm_pp),
  4. Endpoint identifiers (endpoint),
  5. Patch Panel identifiers (lm_patchp).

When a bound_to link is created between two ports, A and B, the wires meta-data on their Patch Panel is updated (they have to be attached to the same Patch Panel). Two entries are added to the wires meta-data map: A => B, B => A.

Each bound_to link between Physical Port and Virtual Port has its corresponding xen bridge (xenbr{X} where X is a number). Before wiring occurs, Physical Port is assumed to be linked to the bridge as part of. The wiring process is responsible for creating a part of link between the bridge and VP.

Each bound_to link between two Virtual Ports has its corresponding xen bridge. The wiring process is responsible for creating an identifier for the xen bridge and its part of links to the Virtual Ports. The bridge name is inbr_vif{X}_vif{Y} where X and Y are vif interfaces' numbers associated with VPs that are linked.

Generating domain config files for Xen

lucet:generate_vh_domain_config(PhysicalHost, VirtualHostNo, MgmtIfMac)

Generates domain config file for Virtual Hosts (not necessarily those with LINCX). This function is intended to be called after wiring is done by lucet:wire/2.

The VirtualHost is a name for VH identifier as string or binary (or list of names). The MgmtIfMac is the MAC address of the Management Interface that will be set for the first bridge.

Below is an example call:

lucet:generate_vh_domain_config(<<"PH1">>, 1, "00:01:02:03:04:05").
vif = ['mac=00:01:02:03:04:05,bridge=xenbr0',
       'bridge=inbr_vif1.2_vif2.1',
       'bridge=xenbr1']

Generating topologies

Lucet comes with a JSON topology generator for Dobby. It can be run like:

./utils/appfest_gen -out appfest.json -physical_ports 10 -physical_hosts 4 \
-ofp_ports 4 -virtual_hosts 1

The script takes the following options:

Options Description Default
out The output file "out.json"
physical_hosts Number of physical hosts (ph) 2
physical_ports Number of physical ports (pp) per ph 4
virtual hosts Number of virtual hosts (vp) with endpoints (ep) 1
ofp_ports Number of OpenFlow ports per vh with OpenFlow switch (ofs) 4

Note that the virtual_hosts parameter does not take into account Virtual Host no 1 which is always assumed to be VH with OFS.

Example

To see larger pictures open them as raw github content.

This example illustrates how to use Lucet to wire a topology generated with the following command:

./utils/appfest_gen -out topo.json -physical_ports 1 -ofp_ports 2 -virtual_hosts 1 -physical_hosts 2

A picture below shows the topology in the Dobby Visualizer tool:

example1

After the wiring we expect that:

  1. Port 1 of OpenFlow Switch 1 on Physical Host 1 (PH1/VH1/OFS1/OFP1) will be bound to Port 1 of OpenFlow Switch 1 on Physical Host 2 (PH2/VH1/OFS1/OFP1). This indicates that:
    1. On Physical Host 1, Port 1 of OpenFlow Switch 1 (PH1/VH1/OFS1/OFP1) will be bound to Physical Port 1 (PH1/PP1),
    2. On Physical Host 2, Port 1 of OpenFlow Switch 1 (PH2/VH1/OFS1/OFP1) will be bound to Physical Port 1 (PH2/PP1).
  2. On Physical Host 1, Port 2 of OpenFlow Switch 1 (PH1/VH1/OFS1/OFP2) will be bound to Endpoint1 on Virtual Host 2.
  3. On Physical Host 1, Port 2 of OpenFlow Switch 1 (PH2/VH1/OFS1/OFP2) will be bound to Endpoint1 on Virtual Host 2.

Importing the topology file into Dobby

Start the Dobby service and import the topology json file:

dby_bulk:import(json, "{PATH}/out.json").

Verify that the topology is imported:

3> dby:links(<<"PH1">>).
[{<<"PH1/PP1">>,
  #{<<"type">> => #{publisher_id => <<"lucet">>,
      timestamp => <<"2015-05-26T16:22:02Z">>,
      value => <<"part_of">>}}}]

Wiring OpenFlow ports

Before calling Lucet API make sure that it is connected to Dobby. Calling nodes() in Lucet shell should return something like ['[email protected]'].

lucet:wire(<<"PH1/VH1/OFS1/OFP1">>, <<"PH1/PP1">>).
lucet:wire(<<"PH1/PP1">>, <<"PH2/PP1">>).
lucet:wire(<<"PH2/VH1/OFS1/OFP1">>, <<"PH2/PP1">>).

Now, the topology representation should look like on the picture below:

example1

In comparison to the initial picture there are 2 new identifiers:

  1. Xen bridge between PH1/PP1 and PH1/VP1.1 called PH1/xenbr1. The bridge number is taken from the interface metadata of PH1/PP1.
  2. Similar bridge between PH2/PP1 and PH2/VP1.1 called PH2/xenbr1.

There are also 9 new links:

  1. A part_of link between PH1/xenbr1 and PH1/PP1.
  2. A part_of link between PH1/xenbr1 and PH1/VP1.1.
  3. A bound_to link between PH1/PP1 and PH1/VP1.1.
  4. A connected_to link between PH/PP1 and PH1/VH1/OFS1/OFP1.
  5. 4 analogous links to 1. 2. 3. and 4. for PH2.
  6. A connected_to link between PH1/PP1 and PH2/PP1.

We cannot do it with

lucet:wire(<<"PH1/VH1/OFS1/OFP1">>, <<"PH2/VH1/OFS1/OFP1">>)

because Lucet wouldn't know which PPs to use (for example it could choose that PP1/PP1 will be connected to PH2/PP3). However, if we want to have a connected_to link between the OpenFlow Ports we can call

lucet:wire(<<"PH1/VH1/OFS1/OFP1">>, <<"PH2/VH1/OFS1/OFP1">>).

after all the above commands.

Wiring Endpoints with OpenFlow ports

lucet:wire(<<"PH1/VH1/OFS1/OFP2">>, <<"PH1/VH2/EP1">>).
lucet:wire(<<"PH2/VH1/OFS1/OFP2">>, <<"PH2/VH2/EP1">>).

After this call the topology will change into this:

example1

In comparison to the previous state it has 2 new identifiers, and 8 new links. The identifiers are:

  1. Xen bridge between Virtual Ports of Virtual Host 1 and 2 on Physical Host 1: PH1/inbr_vif1.2_vif2.1
  2. Xen bridge between Virtual Ports of Virtual Host 1 and 2 on Physical Host 2: PH2/inbr_vif1.2_vif2.1.

And the links:

  1. A part_of link between PH1/inbr_vif1.2_vif2.1 and PH1/VP1.2.
  2. A part_of link between PH1/inbr_vif1.2_vif2.1 and PH1/VP2.1.
  3. A bound_to link between PH1/VP1.2 and PH1/VP2.1.
  4. A connected_to link between PH1/VH1/OFS1/OFP2 and PH1/VH2/EP1.
  5. 4 analogous links to the above but for PH2.

Generating Xen config files for the VHs

For PH1/VH1:

lucet:generate_vh_domain_config(<<"PH1">>, 1, "00:01:02:03:04:05").
vif = ['mac=00:01:02:03:04:05,bridge=xenbr0',
       'bridge=inbr_vif1.2_vif2.1',
       'bridge=xenbr1']

For PH1/VH2:

lucet:generate_vh_domain_config(<<"PH1">>, 2, "00:01:02:03:04:05").
vif = ['mac=00:01:02:03:04:05,bridge=xenbr0',
       'bridge=inbr_vif1.2_vif2.1']

And analogously for the PH2 Virtual Hosts.