[Trema] A good example with Trema to build OpenFlow Controller ( use case )

Previously I just wondered how to use Trema to build a useful and piratical solution with a good architecture for users to leverage its functionality. Well, it does exist. The following URL is a good example of a good use case containing a good architecture.
http://www.slideshare.net/chibayasunobu/developing-production-open-flow-controller-with-trema-201304160

Source Code:
https://github.com/trema/virtual-network-platform


Design:

Implementation:

[Trema] How to install Trema-edge on Ubuntu10.04

Installing Trema-edge needs to use the version of Ruby that is greater than 1.9. In best situation, version 2.0 is best.

1. Install Ruby 2.0
http://www.jeffduckett.com/blog/18/installing-ruby-2-0-0.html

> wget http://ftp.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p0.tar.gz
> tar zxvf ruby-2.0.0-p0.tar.gz
> cd ruby-2.0.0-p0
> ./configure --prefix=/usr/local
> make
> sudo make install
> sudo apt-get -y install libreadline-ruby libopenssl-ruby
> sudo gem update --system
> gem -v

2. Install Bundler
> sudo gem install bundler

3. Clone Trema-edge source code
> git clone https://github.com/trema/trema-edge

4. Install sqlite3 and sqlite3-dev
> sudo apt-get install sqlite3 libsqlite3-dev

5. Build Trema-edge
(In your trema-edge directory)
> sudo bundle install
> sudo rake

6. Try a sample
> ./trema run src/examples/learning_switch/learning-switch.rb -c src/examples/learning_switch/sample.conf

[Trema] The L2 isolation mechanism in sliceable switch

If someone has ever seen the documents about sliceable switch as below, he/she will feel headache or sick because of a lot of contents and description.
https://github.com/trema/apps/wiki/sliceable_switch_tutorial
https://github.com/trema/apps/wiki/sliceable_switch_features

Now, I will give a flow control chart of slice function which is summarized from the source code ( slice.c ). That can give you a clear image about L2 isolation mechanism in sliceable switch, specially in Slice function. Check it out as the following chart:

 So, broadly speaking, the slice function will check mac binding first, then port_mac binding, and finally port binding. Meanwhile, some configurations will affect the result, for instance, "restrict hosts on port" enabled will force the slice function to check port_mac binding, otherwise, it won't do that.
Based on this flow chart, you can compare with the test cases in https://github.com/trema/apps/wiki/sliceable_switch_features

[Trema] How to sync threads using ZeroMQ in Trema

If someone is familiar with Trema, then he/she knows that the socket mode in Trema is non-blocking, which means there is no waiting when sending the request message. But, here is an question. If we want to use ZeroMQ ( in different thread ) to receive the flow stats request from outside world and how do we sync threads and get flow stats info from OFSwitch?

My approach uses "pthread mutex". The key point is in the red box as following picture. When Zmq_Responder receives flow stats request, it will run a callback function, lock the mutex variable, and send flow stats request to OF Switch ( it is non-blocking socket mode ). After sending, Zmq_Responder will be locked and will wait for OF Switch to reply flow stats message. Once it replies, Routing Switch in the main thread will produce the reply message and unlock the mutex variable and let Zmq_Responder to reply to outside world.

The approach can sync these two threads in the sequence, but also has some kind of dead-lock risk. If some one has a better solution, let me know if you are willing.

[Trema] Try the cucumber scenarios in Trema

When you install Trema ready, you can try this in Trema path:
trema> sudo cucumber -r features

And then you will get a lot of log and info on screen. For instance, this is what I got:

Failing Scenarios:
cucumber features/example.message.echo_reply.feature:8 # Scenario: Send echo reply x 10
cucumber features/example.message.echo_reply.feature:18 # Scenario: Send echo reply x 10 in Ruby
cucumber features/example.message.echo_request.feature:8 # Scenario: Send echo request x 10
cucumber features/example.message.echo_request.feature:18 # Scenario: Send echo request x 10 in Ruby
cucumber features/example.message.features_request.feature:8 # Scenario: Send a features request
cucumber features/example.message.features_request.feature:48 # Scenario: Send a features request in Ruby
cucumber features/example.message.hello.feature:8 # Scenario: Hello trema
cucumber features/example.message.hello.feature:18 # Scenario: Hello trema in Ruby
cucumber features/example.message.set_config.feature:8 # Scenario: set config x 10
cucumber features/example.message.set_config.feature:19 # Scenario: set config x 10 in Ruby
cucumber features/example.packetin_filter_config.feature:8 # Scenario: add filter
cucumber features/example.packetin_filter_config.feature:23 # Scenario: dump filter
cucumber features/example.packetin_filter_config.feature:40 # Scenario: dump filter strict
cucumber features/example.packetin_filter_config.feature:62 # Scenario: delete filter strict
cucumber features/example.packetin_filter_config.feature:83 # Scenario: delete filter
cucumber features/packetin_filter.feature:8 # Scenario: packetin_filter --help
cucumber features/packetin_filter.feature:33 # Scenario: packetin_filter -h
cucumber features/switch_manager.feature:8 # Scenario: switch_manager --help
cucumber features/switch_manager.feature:26 # Scenario: switch_manager -h

84 scenarios (19 failed, 65 passed)

417 steps (19 failed, 47 skipped, 351 passed)

7m0.821s

Or if you want to further test Trema/Apps, for instance, sliceable_switch app, you can do this:
trema> sudo cucumber -r features -r ../apps/sliceable_switch/features /home/liudanny/SourceCode/apps/sliceable_switch/features/port_binding.feature
But, I am not sure it is correct way or not and will figure it out.

[Trema] The real case to test flow-based ECMP Routing Switch App

The following picture is a topology that used in testing my ECMP Routing Switch App.

After host3 send packets to host1, the app starts making path process and the related log as below. You will see this app picks up 2 paths ( "0xe5->0xe3->0xe4"  and  "0xe5->0xe2->0xe4" ) and choose one of them to setup flow entries.

[pickup_next_candidate] Find a candidate = 0xe5
[update_distance] node = 0xe3, distance = 1
[update_distance] node = 0xe2, distance = 1
[pickup_next_candidate] Find a candidate = 0xe3
[update_distance] node = 0xe1, distance = 2
[update_distance] node = 0xe4, distance = 2
[update_distance] node = 0xe2, distance = 1
[pickup_next_candidate] Find a candidate = 0xe2
[update_distance] node = 0xe1, distance = 2
[update_distance] node = 0xe4, distance = 2
[pickup_next_candidate] Find a candidate = 0xe1
[pickup_next_candidate] Find a candidate = 0xe4
[build_hop_list] build a hop = 0xe4
[build_hop_list] build a hop = 0xe3
[build_hop_list] build a hop = 0xe5
[resolve_path] find a hop list 0
[pickup_next_candidate] Find a candidate = 0xe5
[update_distance] node = 0xe2, distance = 1
[pickup_next_candidate] Find a candidate = 0xe2
[update_distance] node = 0xe1, distance = 2
[update_distance] node = 0xe4, distance = 2
[pickup_next_candidate] Find a candidate = 0xe1
[pickup_next_candidate] Find a candidate = 0xe4
[build_hop_list] build a hop = 0xe4
[build_hop_list] build a hop = 0xe2
[build_hop_list] build a hop = 0xe5
[resolve_path] find a hop list 1
[resolve_path] has 2 paths, pick up the key = 0 from hash_value = 2169503748

[Trema][Concept] How to do flow-based ECMP in Routing Switch App

  As we have known that Routing Switch App uses Dijkstra algorithm to pick up the lowest cost of the path. Only one path will be selected. If we want to do flow-based ECMP, how to do it? I have a simple way to slightly modify the Routing Switch App and then it can become "ECMP Routing Switch" App.

  Here is a topology as follows. If the source is PC1 and destination is PC2, we can know that the source switch is A and destination switch is B. I will base on this to explain my idea.

  First, we setup a number of multi-path , for instance, 8, and let the loop to do Dijkstra algorithm these times.
  Second, we need to add a new chosen flag to record nodes in the path that we have picked up, and get rid of the source and destination node. And also, when Dijkstra algorithm is running, we also need to add a condition to avoid from choosing the node whose chosen flag is true.

For instance, Path 1 is A->B->C->D. We need to add flag on B and C as true.
                        Path 2 is A->E->F->D. We need to add flag on E and F as true.

In this case, Dijkstra algorithm is not able to pick up the third path so that making paths is done.
I have implemented this in Routing Switch App and it works. I will post the real case in the next article.

[Trema] Provide a monitoring application to watch port and flow loading

I currently provide a initial version of monitoring application to watch port and flow loading information. Here are some items about the configuration and criteria for sending notification.

The configuration

• port_percentage_condition

• the threshold of port loading percentage

• port_setting_feature_rate

• the speed rate of port

• flow_bit_rate_conditon

• the threshold of flow loading

• flow_times_condition

• how many seconds will flow become big flow when being over the threshold of flow loading

The notification criteria of Port Loading

• Check port loading per 4 seconds

• Calculate the percentage of port loading

• port_bit_rate = avg_rx_bytes * 8
• port_loading_percentage = port_bit_rate * 100 / port_feature_rate

• If the port loading percentage is higer than port_percentage_condition, then it sends port loading notification

The notification criteria of Flow Loading

• Check port loading per 4 seconds

• Calculate the flow loading ( flow_bit_rate )

• flow_bit_rate = bytes_count * 8 / duration seconds

• If flow_bit_rate  is bigger than flow_bit_rate_condition, then flow_times adds 1.

• If flow_times is higher than flow_times_condition, for instance, 3, then it sends flow loading notification

[How To] Add ZeroMQ in Trema App

If someone wants to add the mechanism of ZeroMQ to send message from Trema Application, for instance, Routing_Switch, there are several things that need to do and I have tested OK.

Example Trema App: Routing_Switch

1. Install ZeroMQ

• Please follow the instruction from the offical web site: http://www.zeromq.org/intro:get-the-software

2. Modify its Makefile: 

• add the include folder location of ZeroMQ :

• CFLAGS = $(shell $(TREMA)/trema-config --cflags) -I/home/liudanny/SourceCode/zeromq2-1/include -I../topology -g -std=gnu99 -D_GNU_SOURCE -fno-strict-aliasing -Werror -Wall -Wextra -Wformat=2 -Wcast-qual -Wcast-align -Wwrite-strings -Wconversion -Wfloat-equal -Wpointer-arith

• add library name of zeroMQ and link it:
• LDFLAGS = $(shell $(TREMA)/trema-config --libs) -lzmq -L../topology -ltopology

3. Write your ZeroMQ code in Routing_Switch.

[How to][Trema] Get Flow_Removed message in routing_switch app

I asked an question about how to get Flow_Removed message in routing_switch app. But, soon I realized that I asked a stupid one because the answer is also in OpenFlow Spec v1.0.0.
We should set a "OFPFF_SEND_FLOW_REM" flag into "Flow Mod" message when we want to set a flow. The following list is the discussion message log.

================================================================ 
Hi,


If you want to receive "Flow Removed" message, you have to set
"OFPFF_SEND_FLOW_REM" flag into "Flow Mod" message when you set the flow.


Currently "routing_switch" app does not set this flag, then switches does
not send "Flow Removed" message.

================================================================
Hi,
  I try to get "Flow_Removed" message in routing_switch app, but do not see any one coming in.
The following is what I have done in the app and could someone tell me how to fix or modify it?
Many thanks.


Add it in main():
  set_flow_removed_handler( handle_flow_removed, routing_switch );


Add a method for display:
void handle_flow_removed( uint64_t datapath_id, flow_removed message ) {
  routing_switch *routing_switch = message.user_data;
  info( "[handle_flow_removed] dpid = %#" PRIx64 ", match = %s",
          datapath_id, message.match );
}


Modify routing_switch.conf:
vswitch {
  datapath_id "0xe0"
}
vhost ("host1") {
  ip "192.168.0.1"
  netmask "255.255.0.0"
  mac "00:00:00:01:00:01"
}
vhost ("host2") {
  ip "192.168.0.2"
  netmask "255.255.0.0"
  mac "00:00:00:01:00:02"
}
link "0xe0", "host1"
link "0xe0", "host2"


run {
  path "../apps/topology/topology"
}
run {
  path "../apps/topology/topology_

discovery"
}
run {
  path "../apps/routing_switch/routing_switch"
}


event :port_status => "topology", :packet_in => "filter", :state_notify => "topology", :flow_removed => "routing_switch"
filter :lldp => "topology_discovery", :packet_in => "routing_switch"

[Explanation][Trema] The message mechanism in flow_manager app

I give 2 pictures to illustrate the message mechanism in flow_manager app.

1. Request/Reply message using send_request_message() and send_reply_message()

2. (Received) Message using send_message()

[Explanation][Trema] The Register Event in Routing Switch App

If we want to understand how Routing Switch App works in Trema, we have to know the event register first. Here is a simple explanation about the register event in Routing Switch App, which is related Topology Ap.

[Trema] Try Trema App: flow_dumper

1. Choose "routing_switch" as my testing app. (any other simple switch app is all available...)
> ./trema run -c ../apps/routing_switch/routing_switch.conf

2. Send packets between these 2 hosts
> ./trema send_packets -s host2 -d host1
> ./trema send_packets -s host1 -d host2

3. Try to run Trema App: "flow_dumper" as follows
> TREMA_HOME=. ../apps/flow_dumper/flow_dumper
[0x000000000000e0] priority = 65535, match = [wildcards = 0, in_port = 1, dl_src = 00:00:00:01:00:02, dl_dst = 00:00:00:01:00:01, dl_vlan = 65535, dl_vlan_pcp = 0, dl_type = 0x800, nw_tos = 0, nw_proto = 17, nw_src = 192.168.0.2/32, nw_dst = 192.168.0.1/32, tp_src = 1, tp_dst = 1], actions = [output: port=2 max_len=65535]
[0x000000000000e0] priority = 65535, match = [wildcards = 0, in_port = 2, dl_src = 00:00:00:01:00:01, dl_dst = 00:00:00:01:00:02, dl_vlan = 65535, dl_vlan_pcp = 0, dl_type = 0x800, nw_tos = 0, nw_proto = 17, nw_src = 192.168.0.1/32, nw_dst = 192.168.0.2/32, tp_src = 1, tp_dst = 1], actions = [output: port=1 max_len=65535]

4. So, we can see all the flows here.

[Tutorial] Trema Tutorial

http://www.fp7-ofelia.eu/assets/Uploads/201203xx-TremaTutorial.pdf

[Tutorial][Trema] Show Topology

 Trema有一個很不錯的App, 可以利用toplogy與 topology_discovery App, 去產生topology graph…如下:

下列為Network emulation的設定檔內容

# virtual switches

vswitch("switch1") { datapath_id "0x1" }

vswitch("switch2") { datapath_id "0x2" }

vswitch("switch3") { datapath_id "0x3" }

vswitch("switch4") { datapath_id "0x4" }

vswitch("switch4") { datapath_id "0x5" }

# virtual hosts

vhost("host1")

vhost("host2")

vhost("host3")

vhost("host4")

# virtual links

link "switch1", "switch2"

link "switch1", "switch3"

link "switch2", "switch3"

link "switch2", "switch4"

link "switch2", "switch5"

link "switch3", "switch4"
link "switch3", "switch5"

link "switch4", "switch5"

link "switch4", "host1"

link "switch4", "host2"

link "switch5", "host3"

link "switch5", "host4"