Explanation needed For TCP vs UDP

sagarmistry

I've been getting questions wrong about which protocols use TCP vs UDP.

For example, FTP: file transfer protocol uses TCP, because all packets must be transferred to the other side and this is done via the 3 way handshake method.

UDP can't be used because if packets are dropped, they won't be sent again.


However, is there a complete list somewhere which says this uses TCP and this uses UDP??

I get confused at times and get the question wrong, tried to find the list online but all I could find was port numbers.

Thanks for the help in advance!

NetworkNewb

There are a bunch of sites that list them. Here is one. Common Application Ports - Bandwidth Controller

Might be better exporting that into Excel and arranging them better but that is one example.

BerkshireHerd

TCP is RELIABLE, meaning if a file needs to be transfered in full it goes. because it is reliable it is usully slower. Think about sending a file or email, you want to make sure every packet is sent and put back together in order to have a complete message.

UDP is unreliable, meaning is a packet is dropped along the way, who cares, it gone forever. Think of VOIP, if I'm on a call and I hear a bit of static on the other end will it ruin my converation?, probably not, worst thing would me to ask them to repeat it VOIP uses UDP.


If you look a list of Well Known Ports, which you should know for CCENT, you will see that some ports use UDP and TCP. Like FTP uses TCP but TFTP uses UDP, TFTP is very simple and fast but has no guarantee.

theodoxa

UDP has a lot less overhead than TCP. It is used for Voice and Video because a few lost packets is acceptable in order to get less delay. UDP is used when some packet loss is acceptable or when the L7 protocol (e.g. TFTP) has its own mechanism for dealing with packet loss. As for knowing what protocols use UDP vs. TCP, that is simply something you'll have to memorize. You don't need to know them all - just the common ones like HTTP (TCP), HTTPS (TCP), FTP (TCP), TFTP (UDP), DNS Lookup (UDP), SMTP (TCP), and DHCP (UDP).

Well known SCTP, TCP and UDP ports, 0 through 999

OfWolfAndMan

The most important thing to remember about transport protocols is it's how a flow is handled in the case of errors (L2 and 3 may have error checks, but it can't do anything about it).

UDP has no method of error handling (Hence deemed unreliable), however the overhead for processing is minimal, whereas TCP has higher overhead, but can handle moving a flow's rate around, ensure orderly packet delivery via sequence numbers, Ack numbers, etc.

Theodoxa has a good link there.

MTciscoguy

I did a simple google search UDP vs TCP and returned 1,030,000 hit, figure a couple of hundred thousand of those are bad and really not pertaining to the question, that is still a lot of explanations available for those who know how to search. Every single CCNA book or course explains the differences.

sagarmistry

MTciscoguy wrote: »

I did a simple google search UDP vs TCP and returned 1,030,000 hit, figure a couple of hundred thousand of those are bad and really not pertaining to the question, that is still a lot of explanations available for those who know how to search. Every single CCNA book or course explains the differences.

And what difference did it make to you if other guys here helped me understand in their own words?

Reply only if you want to help.

And thanks guys, I think I get the concept now.

mikeybinec

Video is sent via UDP.. If a packet gets dropped you won't notice it. but if a packet gets dropped from an email, and not resent (as TCP does) you won't be able to read the email..it'll be corrupted

MTciscoguy

sagarmistry wrote: »

And what difference did it make to you if other guys here helped me understand in their own words?

Reply only if you want to help.

And thanks guys, I think I get the concept now.

It matters because based on your hundreds of questions, you are not trying to learn, you are trying to get others to answer the questions for you, you ask questions about the simplistic things, that you should able to find out if you are studying the materials, you have done it since the day you started on here, read the materials, the UDP vs TCP is one of the easiest concepts in the IT business.

Don't try to even tell me what I can reply to, if it gets posted on a public forum, you should expect anyone to reply to your messages. You remind me of some of the guys I had training under me in the Army, guess what, they got sent home.

I have over 30 years working in computers and networks behind me and when I first started on this system, got told, learn the information, if you don't understand it, then ask, but at least try it yourself first, now if you don't want to see my messages, there is an ignore feature in this software, put me on your ignore list. But I will continue to answer as I see fit.

rsutton

sagarmistry wrote: »

And what difference did it make to you if other guys here helped me understand in their own words?

Reply only if you want to help.

And thanks guys, I think I get the concept now.

There is a difference between needing help understanding something, and asking to be spoon fed. Your question implies that you are seeking the latter. You shouldn't be surprised to receive feedback based on that. Many people here have spent long hours researching topics to obtain understanding; your question implies that you do not want to put forth that effort. And for that reason, I'm out.

cyberguypr

TCP vs UDP - Difference and Comparison | Diffen

Compares both apples to apples. As simple a it gets.