2.3.2 DTN Router vs. TCP/IP Router

2.3.2    DTN Router vs. TCP/IP Router

Internet layer used TCP and IP protocols through the network. TCP operates at each end point of the path and manages end to end delivery of message segments. IP operates on all nodes on the path and routes message datagram. Internet routers as shown in Figure 2.18 do not need a transport layer for routing. They only implemented for maintenance purposes.

Figure 2.18: Internet Router [9]

In a DTN, the protocol stacks of all nodes include both bundle and transport layers. DTN gateways have the same double stack layers as DTN routers as shown in Figure 2.19. DTN gateways can run different lower layer protocols on each side of their double stack. This allows DTN gateway to span two regions that use different lower layer protocols.

Figure 2.19: DTN Router [9]

Netbeans IDE With Sencha Touch

1) Requirements:

i) Download the Netbeans IDE (I use the latest version 8):
https://netbeans.org/

ii) Download the latest Sencha plugin from here:
https://bitbucket.org/addicticks/nbplugin-senchacmd/downloads

iii) Download the Sencha Touch library from here(I use latest touch-2.4.1, rename it as touch):
http://www.sencha.com/

2) Create new project

Choose New>Java Web>Web Application. Press the Next button. Name the app “SenchaApp”. Choose the project location. Press the Next button.

Select Tomcat as the servers and click the Finish button.

3) Prepare Sencha App Structure

i) Inside web folder, create the app folder, views folder, models folder, controllers folder in NetBeans to add your javascript files into.

ii) Add previously download "touch" folder into web folder.

4) Add sencha library

i) Right click on the SenchaApp application and select Properties from the drop down menu

ii) Under the Libraries menu, choose “Add Libraries” and from the window that opens click “Create…”

iii) Name the Library “Sencha_Touch” and choose “Class Library” from the drop down.

iv) Under the “Classpath” tab, click on “Add JAR/Folder” and select the “touch” folder previously downloaded.

v) Click “OK” and choose the newly created “Sencha_Touch” library.

create an app.js file in the app folder. Type Ext followed by a “.” — If the steps above were followed correctly, the code completion should work.

5) Code/create your sencha touch application

6) Run Application

Hit Run.

Your application should start in the default browser with the url : localhost:8084/SenchaApp/

Reference: http://techtalktone.wordpress.com/2012/02/22/using-netbeans-ide-with-sencha-touch/

High CPU activity problem: Stop and disable AVGIDSagent service

AVG user mostly will experience CPU High activity. Computer become slow and hardly to use. This is because of AVGIDSagent service using a lot of the computer resources. Blame AVG for that.
To solve that problem, follow this guide:

1) At tray, Temporary disabled AVG protection.
2) Open Windows Services
3) Open AVGIDSagent service. Stopped the service by changed its status from “Automatic” to “Disabled”
4) Enable AVG protection again.

Everythng is back on high speed as normal.

Reference:
http://www.thefreewindows.com/16279/stop-disable-avgidsagent-service-reduce-cpu-activity/

7zip command to batch zip all folders and unzip all zip files

7zip is very usefull to do batch jobs through command line. I usually use these command and create a batch file for easy use later. Just simply put the command in text file and rename .txt as .bat.

This is command for batch unzip all zip files into each respective folders name:

@echo off
for /F "delims=" %%I IN (' dir /b /s /a-d *.zip ') DO (
    "c:\Program Files\7-Zip\7z.exe" x -y -o"%%~dpI\%%~nI" "%%I"
)
pause

This is command for batch zip all folders into each respective zips name:

for /d %%X in (*) do "c:\Program Files\7-Zip\7z.exe" a "%%X.zip" "%%X\"

2.3 Comparison of TCP/IP and DTN

2.3  Comparison of TCP/IP and DTN

2.3.1     DTN vs. TCI/IP: Protocol Architecture

Internet layers and DTN layers are identical except that DTN architecture implements store and forward message switching by overlaying a new protocol layer called bundle layer. It is placed on top of Transport layers. The bundle layer ties together the Transport layers and below with application programs to communicate across multiple regions. Bundles are also called messages switched. The bundle layer stores and forwards entire bundles or bundle fragments between nodes. A single bundle layer protocol is used across all networks that make up a DTN. By contrast, the layers below the bundle layer which is transport layer and below are chosen for their appropriateness to the communication environment of each region.

Figure 2.14 shows the DTN layer compares to the Internet layer [9]. Bundle consists of a source-application user data, Control Information provided by source application and destination application which describes how to process, store, dispose and handle user data and a Bundle header. Bundles extend the hierarchy of data-object encapsulation performed by the Internet protocols.

Figure 2.14: Comparison Internet Protocol Layers with DTN Protocol Layers

Figure 2.15 shows how bundle-layer encapsulation works in the context of TCP/IP protocols. A bundle layer may break whole bundles or messages into fragments as an IP layer may break a whole datagram into fragments. If bundles are fragmented, the bundle layer at the final destination reassembles them.

Figure 2.15: Bundle Encapsulation [9]

            On intermittently connected links with long delays, conversational protocols such as TCP/IP that involves many end to end round trips may take impractical amounts of times or connectivity failure. To overcome this problem, DTN bundle layers communicate between themselves using simple sessions with minimal or no round trips as shown in Figure 2.16. Acknowledgement from the receiving node is depending on the class of service selected as shown in Figure 2.17. The lower layer protocols that support bundle layer exchange may of course follow the existing TCP. But on intermittently connected links with long delays, minimal conversational lower layer protocols can be implemented [9].

Figure 2.16: Minimal conversational lower layer protocols [9]

The bundle layer provides six classes of Bundle Services:

i.                    Custody Transfer: Responsible of data retransmission to an accepting node. The sending node can recover its retransmission resources. The accepting node returns a custodial acceptance acknowledgement to the previous custodian.

ii.                  Return Receipt: Confirmation to the source. It is a reply to the sender application that the bundle has been received by the destination application.

iii.                Custody Transfer Notification: Notify the source when a node accepts a custody transfer of the bundle.

iv.                Bundle Forwarding Notification: Notify the source when a bundle is forwarded to another node.

v.                  Priority of Delivery

vi.                Authentication: Verify sender identity and message integrity.

In this thesis, the bundle service class (i), (v) and (vi) is used to form a store and forward overlay network and provide the key capabilities of bundle protocol which is custody based retransmission and able to cope with intermittent connectivity [10].

Figure 2.17: Class of Bundle Service [9]