?
Solved

TCP,UDP checksums

Posted on 1997-10-26
1
Medium Priority
?
1,171 Views
Last Modified: 2013-12-23
Hello,
Why do TCP and UDP have their own checksums?Is the IP checksum not enough?
and Why lost TCP acknowledgements do not necessarily force retransmissions?
Thanks.
0
Comment
Question by:bpmf
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
1 Comment
 
LVL 1

Accepted Solution

by:
Joshua111197 earned 400 total points
ID: 1582745
Hey,

TCP and UDP are protocols at the similar OSI-Layer, but UDP is no secure end-to-end-protocol, because no acknoledgements are sent from the destination and a checksum has not to be calculated  (checksum=0 means, no checksum will be calculated). So transmission errors can only be checked by IP checksum.

The TCP-checksum is calculated to secure the transmission of the data from Layer 4 to Layer 3 (IP). The original data will be checked here. The IP checksum will vary on every hop, because the IP header has the source adress and the destination adress of the next hop inside. So with every router on the run the checksum will be a different. The TCP-checksum can controll changings of the original data.

The retransmissions are not builded bye the TCP protocol but bye the application. The RFCs for TCP only describe the TCP-packet but not the applications they are created by. So I think, the ability  to force retransmission depends on the application.

I hope this will answer your questions.

Yours Josh
0

Featured Post

ATEN's HDBaseT Presentation at InfoComm 2017

Hear ATEN Product Manager YT Liang review HDBaseT technology, highlighting ATEN’s latest solutions as they relate to real-world applications during her presentation at the HDBaseT booth at InfoComm 2017.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

WARNING:   If you follow the instructions here, you will wipe out your VTP and VLAN configurations.  Make sure you have backed up your switch!!! I recently had some issues with a few low-end Cisco routers (RV325) and I opened a case with Cisco TA…
This month, Experts Exchange’s free Course of the Month is focused on CompTIA IT Fundamentals.
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…
If you're a developer or IT admin, you’re probably tasked with managing multiple websites, servers, applications, and levels of security on a daily basis. While this can be extremely time consuming, it can also be frustrating when systems aren't wor…

718 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question