Skip to main content

Difference between In Band and Out of Band Protocols

In band
In-band control is a characteristic of network protocols with which data control is regulated. In-band control passes control data on the same connection as main data.In Band Protocols
Protocols that use in-band control include HTTP and SMTP.
SMTP is in-band because the control messages, such as “HELO” and “MAIL FROM”, are sent in the same stream as the actual message content.

Out of Band
In computer networking, out-of-band data (called “urgent data” in TCP) looks — to the application — like a separate stream of data from the main data stream. This can be useful for separating two different kinds of data. Note that just because it is called “urgent data” does not mean that it will be delivered any faster or with higher priority than data in the in-band data stream. Also beware that unlike the main data stream, the out-of-band data may be lost if the application cannot keep up with it. “Urgent data” notifies the receiving connection that the separate stream is more important than the main stream. Therefore it must first check the separate stream in order to process the main stream normally.

To Understand this, cosider the file transfer through FTP Protocol (an Out of Band Protocol)

FTP operates on the application layer of the OSI model, and is used to transfer files using TCP/IP. In order to do this an FTP server needs to be running and waiting for incoming requests. The client computer is then able to communicate with the server on port 21. This connection, called the control connection, remains open for the duration of the session, with a second connection, called the data connection, either opened by the server from its port 20 to a negotiated client port (active mode) or opened by the client from an arbitrary port to a negotiated server port (passive mode) as required to transfer file data.
The control connection is used for session administration (i.e., commands, identification, passwords) exchanged between the client and server using a telnet-like protocol.

For example “RETR filename” would transfer the specified file from the server to the client. Due to this two-port structure, FTP is considered an out-of-band protocol.

Comments

Popular posts from this blog

Connection control operation failed for disk 'ide1:0'

I was getting this error while removing Operating System ISO image mounted on the Virtual Machine.

What worked for me, is
1. Uncheck the "Connected and Connect at power on" from Device Status.
2. Then Change the Device type from "Datastore ISO File to Client Device" Radio Button
3. and press OK to save the changes.

Note:- I was able to remove the mounted ISO only by directly logging to the ESXi at https://esxi-ip-address/ui

where it asks

"The guest operating system has locked the CD-ROM door and is probably using the CD-ROM, which can prevent the guest from recognizing media changes. If possible, eject the CD-ROM from inside the guest before disconnecting. Disconnect anyway and override the lock?"

You need to select yes to eject the CD-ROM and then remove the ISO file successfully.

a file I/O error has occurred while accessing vmware converter

While converting physical Windows 7 machine to Virtual machine of infrastructure type, I got this error. The error seems it is unable to read/write source or destination datastore.

I have installed VMware-converter-en-6.2.0-8466193 on Windows 7 physical machine with option locally selected. (not at server/client option)

All of my ESXi servers are connected to the vCenter Server, so I had to use vCenter Server's IP address to send this physical machine to the virtual world.

The issue i found was with the dns resolution to the vCenter Server's hostname. Since I am not using the same dns server on the Windows 7 client machine. So I updated the host entries manually for the vCenter Server's hosname to it IP address.

After adding dns eteries to the hostfile of windows 7, I am not getting this "a file I/O error has occurred while accessing vmware converter" and the migration has started.

How to import Putty Saved Connections to mRemoteNG

Just started using mRemoteNG and its being very cool to connect to different remote connection with different protocols e.g Window Remote Desktop, VNC to Linux, SSH, HTTP connection etc. from a single application.

As new user I configured some remote desktop connection which was quite easy to figure out. But when I wanted to add SSH connections, it came in my mind to import all of the saved connections in the putty. But I couldn't figure it out how can it be done, though it was quite easy and here are the steps.


Open your mRemoteNGCreate a folder if you want segregation of multiple networksCreate a new connectionEnter the IP address of remote server under connection in Config paneUnder the config pane, select protocol "SSH version 2".  Once you select protocol to SSH version 2 you are given option to import putty sessions, as shown in the snap below.


In the above snap, I have imported CSR-AWS session from my saved sessions in Putty.