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Important: This tutorial does not use any of the files in this repo. So you do not have to clone this repo if you are JUST following THIS tutorial.

Goal: Seting up LINC-OE simple optical topology with iControl.

Requirements: A basic knowlege of LINC-OE, TAP interfaces, Erlang language and linux CLI is required.

Road Map: This document has two sections for setup:

  1. setting up the iControl
  2. setting up the linc-oe

After seting up the above two sections, we can install flows and send packets.

At the end I have provided some usefull functions and references.

1. setting up/running the iControl

If you haven't clone the LOOM repo, do the following:

	git clone https://github.com/FlowForwarding/loom.git

if you already have cloned the LOOM repo. Build and Run the icontrol:

Build icontrol:

	cd icontrol
	make

Run:

	rel/icontrol/bin/icontrol console

This document shows how to use LINC-Switch to simulate simple optical network like on the diagram below:

2. setting up the linc-oe

Here is the topology:

           |       (1)       |      |      (2)       |      |       (3)       |
[tap0]-----|[1]  <PO-SW>  [2]|~~~~~~|[1]  <O-SW>  [2]|~~~~~~|[1]  <PO-SW>  [2]|-----[tap1]
 (OS)      |     (LINC)      |      |     (LINC)     |      |      (LINC)     |      (OS)
  • (X) - is the logical switch number
  • PO-SW - indicates packet-optical logical switch (i.e. a switch that has Ethernet ports as well as optical ones)
  • O-SW - indicates optical switch (i.e. a switch that has only internally emulated optical ports and links between them)
  • [tapX] - is the operating system tap interface number X
  • ---- line is the packet link

Operating system configuration

To run the simulation two tap interfaces are required. Following commands show how to configure them in Linux:

sudo tunctl -t tap0
sudo tunctl -t tap1
sudo ip link set dev tap0 up
sudo ip link set dev tap1 up

LINC-OE configuration

rel/files/sys.config file for the network shown above should looks as following:

[{linc,
  [{of_config,disabled},
   {capable_switch_ports,
    [{port,1,[{interface,"tap0"}]},
     {port,2,[{interface,"dummy"}, {type, optical}]},
     {port,3,[{interface,"dummy"}, {type, optical}]},
     {port,4,[{interface,"dummy"}, {type, optical}]},
     {port,5,[{interface,"dummy"}, {type, optical}]},
     {port,6,[{interface,"tap1"}]}
    ]},
   {capable_switch_queues, []},
   {optical_links, [{{1,2}, {2,1}}, {{2,2},{3,1}}]},
   {logical_switches,
    [{switch,1,
      [{backend,linc_us4_oe},
       {controllers,[{"Switch0-Controller","localhost",6653,tcp}]},
       {controllers_listener,disabled},
       {queues_status,disabled},
       {datapath_id, "00:00:00:00:00:01:00:01"},
       {ports,[{port,1,[{queues,[]}, {port_no, 1}]},
               {port,2,[{queues,[]}, {port_no, 2}]}
              ]}]},
     {switch,2,
      [{backend,linc_us4_oe},
       {controllers,[{"Switch0-Controller","localhost",6653,tcp}]},
       {controllers_listener,disabled},
       {queues_status,disabled},
       {datapath_id, "00:00:00:00:00:01:00:02"},
       {ports,[{port,3,[{queues,[]}, {port_no, 1}]},
               {port,4,[{queues,[]}, {port_no, 2}]}
              ]}]},
     {switch,3,
      [{backend,linc_us4_oe},
       {controllers,[{"Switch0-Controller","localhost",6653,tcp}]},
       {controllers_listener,disabled},
       {queues_status,disabled},
       {datapath_id, "00:00:00:00:00:01:00:03"},
       {ports,[{port,5,[{queues,[]}, {port_no, 1}]},
               {port,6,[{queues,[]}, {port_no, 2}]}
              ]}]}
    ]}]},
 {of_protocol, [{no_multipart, false}]},
 {enetconf,
  [{capabilities,[{base,{1,1}},{startup,{1,0}},{'writable-running',{1,0}}]},
   {callback_module,linc_ofconfig},
   {sshd_ip,any},
   {sshd_port,1830},
   {sshd_user_passwords,[{"linc","linc"}]}]},
 {epcap,
  [{verbose, false},
   {stats_interval, 10},
   {buffer_size, 73400320}]},
 {lager,
  [{handlers,
    [{lager_console_backend,debug},
     {lager_file_backend,
      [{"log/error.log",error,10485760,"$D0",5},
       {"log/debug.log",debug,10485760,"$D0",5},
       {"log/console.log",info,10485760,"$D0",5}]}]}]},
 {sasl,
  [{sasl_error_logger,{file,"log/sasl-error.log"}},
   {errlog_type,error},
   {error_logger_mf_dir,"log/sasl"},
   {error_logger_mf_maxbytes,1048576000000},
   {error_logger_mf_maxfiles,5}]},
 {sync,
  [{excluded_modules, [procket]}]}].

Here is what we have:

Alt text

Reminder

To assign a port to a logical switch two requirements has to be met:

  1. the port has to be defined in the capable_switch_ports.
  2. the port has to be listed in the ports for the logical switch.

Note that logical switch port numbers do not have to be the same as capable switch port numbers. If the port_no option is not provided it defaults to capable switch port number.

If port_name option is not provided it defaults to Port{LOGICAL_SWITCH_PORT_NO} or Port{CAPABLE_SWITCH_PORT_NO} if logical port number is not provided.

Starting LINC-OE

Go to the directory where the linc switch repo is cloned. For me I have it in ~/linc-oe so:

$ cd ~/linc-oe

Build LINC-Switch and run it:

  $ make rel && sudo rel/linc/bin/linc console

Note that based on your account priviliage you may have to run it with sudo.

Usage

So now you have both the linc-oe and iControll set up. Time to play with them.

On one end you have a switch connected to Tap 0 and on the other end you have switch conneted to tap. Switches connect the two tap interfaces. But, If you put packets on one tap and monitoor the other tap, you will not recieve any packets. Why? Because iController needs to insert/instal flows on switches so that a path is created from tap 0 to tap 1. Let's create that path:

Before we start I should mention that in optical networks packet ports are marked as T while optical ones as W. Thus we have a function called oe_flow_tw where tw means "from port T to port W".

(icontrol@127.0.0.1)> iof:oe_flow_tw(2,100,1,2,20).

Install a flow on switch 1 that will forward packets from port 1 to the optical link connected to port 2 using wavelength 20. Remeber that port 1 of switch with key 2 is connected to tap0. Note that switch with key=2 has a switch id=1. Switch id is the one that you set in the sys.config file. -> I don't know why they are different.
Here switch with key 2 and switch id of 1 has one connection to a tap interface and one connection to optical link.

(icontrol@127.0.0.1)> iof:oe_flow_ww(1,100,1,20,2,20).

For switch with key 1, this will Install a flow on switch 2 that will take optical data from channel 20 on port 1 and put it on port 2 into the same channel. Here switch with key 1 and switch id of 2 is the middle switch. So there is no tap interface connected to it and has two optical connection. That's why we use oe_flow_ww.

(icontrol@127.0.0.1)> iof:oe_flow_wt(3,100,1,20,2).

For switch with key 2, this will Install a flow on switch 3 that will take optical data from channel 20 on port 1 and convert it back to packet data and send it through port 2

Observing the traffic

So now we have created the path from tap0 to tap1. Lets put some packet in tap0 and see if we can receive it on tap1.

  1. Double check the path. See if all the flows are installed properly using :
iof:flows(<Switch key>).

  1. Start Wireshark/tcpdump on port tap1

  2. Examine the counters of the flow installed on switches

    (icontrol@127.0.0.1)12> iof:flows(SwitchKey).

    For example, I get the following message when I run (icontrol@127.0.0.1)> iof:flows(1). 

    {ofp_flow_stats_reply,[],
[{ofp_flow_stats,0,4,424046000,100,0,0,[],
     <<0,0,0,0,0,0,0,10>>,
     0,0,               % <--------- packet and byte counters of the flow entry
     {ofp_match,
         [{ofp_field,openflow_basic,in_port,false,<<0,0,0,1>>,undefined},
          {ofp_field,infoblox,och_sigtype,false,<<"\n">>,undefined},
          {ofp_field,infoblox,och_sigid,false,
              <<1,2,0,20,0,1>>,
              undefined}]},
     [{ofp_instruction_apply_actions,2,
          [{ofp_action_experimenter,99,7636849,
               {ofp_action_set_field,13,
                   {ofp_field,openflow_basic,och_sigid,false,
                       <<1,2,0,20,0,1>>,
                       undefined}}},
           {ofp_action_output,16,2,no_buffer}]}]}]}

    I get the following message when I run (icontrol@127.0.0.1)> iof:flows(2). 

    {ofp_flow_stats_reply,[],
[{ofp_flow_stats,0,6,688447000,100,0,0,[],
     <<0,0,0,0,0,0,0,10>>,
     0,0,
     {ofp_match,
         [{ofp_field,openflow_basic,in_port,false,<<0,0,0,1>>,undefined}]},
     [{ofp_instruction_apply_actions,2,
          [{ofp_action_experimenter,99,7636849,
               {ofp_action_set_field,13,
                   {ofp_field,openflow_basic,och_sigid,false,
                       <<1,2,0,20,0,1>>,
                       undefined}}},
           {ofp_action_output,16,2,no_buffer}]}]}]}

    I get the following message when I run (icontrol@127.0.0.1)> iof:flows(3). 

    

    3. 



{ofp_flow_stats_reply,[],
[{ofp_flow_stats,0,115,967092000,100,0,0,[],
<<0,0,0,0,0,0,0,10>>,
0,0,
{ofp_match,
[{ofp_field,openflow_basic,in_port,false,<<0,0,0,1>>,undefined},
{ofp_field,infoblox,och_sigtype,false,<<"\n">>,undefined},
{ofp_field,infoblox,och_sigid,false,
<<1,2,0,20,0,1>>,
undefined}]},
[{ofp_instruction_apply_actions,2,
[{ofp_action_output,16,2,no_buffer}]}]}]}
```


    

  1. 

    Send ping through tap0
    

    $ sudo tcpreplay -i tap0 ~/linc-oe/pcap.data/ping.pcap
    

    

    If tcpreply is not installed, follow these instructions:
https://github.com/Ehsan70/Mininet_LINC_script/blob/master/Install_tcpreply.md
    

    

    2. 

  2. 

    In the Wireshark verify that the packet got to the other end and check the flows stats once again.
    

    3. 



Useful Funtions:


Clearing flows in specific switch


Clears flows in switch with key equal to .


iof:clear_flows(<Switch key>). 



Flows


Dumps flows in switch with key equal to .


iof:flows(<Switch key>).  



Further Functions###


For further functions see this .md file from loom repository.


Additional Sources


This tutorial was made from a comnination of the following tutorials:


https://github.com/FlowForwarding/LINC-Switch/blob/master/docs/optical_extension.md


https://github.com/FlowForwarding/loom/tree/master/icontrol