Solved

Few more UDP Questions

Posted on 2004-04-23
4
246 Views
Last Modified: 2010-04-11
Hey
almost finished my coursework ( u'll all be happy about that) just a few more really basic questions to go!

1.  I have basically created a header for the Application level that contains all the necessary info to process by my protocol! however i was just wondering i havent added source and destination fields at this level because i thought that at this level it was really at the location it needed to be at. Do i need to include the Source and destination fields at this level?

                       HOST 1                                   HOST 2
                          |                                            |
Send Packet 1      | -------------------------------->|
                          |                                            |
                          | <--------------------------------|Acknowledge Packet 1
                          |                                            |
                          |                                            |
                          |                                            |

2. The above diagram shows a simple sent packet and ACK but just say HOST2 trys to send a NAC to Host 1. Is there much point using Nac's over UDP?
I dont think so because what happens if the NAC fails to get to Host1. Wouldnt it just be easier to wait fot Host 2 to wait for Host1 to timeout and resend?

3. What are PDU's and how would i actually construct them\ it in relation to my protocol? what sort of things do they need to include?

i know this probably seems very trivial! but any thoughts would be great?

cheers

ed
0
Comment
Question by:Follette
[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
4 Comments
 
LVL 17

Expert Comment

by:RDAdams
ID: 10901637
We are not supposed to assist with homework.
0
 
LVL 11

Accepted Solution

by:
PennGwyn earned 50 total points
ID: 10901678
1.  There will be source and destination addresses in the IP/UDP header -- and these will be updated in transit, if necessary, due to NAT.  Embedding addresses inside the payload, where NAT won't see them, is the classic way protocols get broken by NAT.  So any source/dest info the application needs should come from the IP header and not from the payload.

2.  You can get away with just timeouts, but if this is an interactive application then users may complain.  An explicit NAK signals the host to retransmit immediately instead of waiting for a timeout.

3. PDU ("Protocol Data Unit") is a layer-independent term for frame, packet, segment, or whatever the protocol passes to the underlying layer (and gets back from it when receiving); the protocol payload without any of the headers that get added by encapsulation as it is prepared for transmission.

0
 
LVL 7

Expert Comment

by:PaulADavis
ID: 10901778
i don't quite understand what you are doing... but i'll add a little 2cents , maybe only worth one :-)

from my understanding pdu's are protocol data units, that's used by each layer of the osi or tcp/ip stack to exchange information with it's corresponding layer at the destination.
it's a fair assumtion to say that they would need to include information that allows each layer to complete it's function and pass it on to the next layer...

but this is out of my scope really :-)

so, all the best to you.
0
 

Author Comment

by:Follette
ID: 10902687
Thats really useful thanks pennGywnn and cheers Paul... really the last question now then i think im done!

is the PDU basicalloy just a descrition of the Header i will have made! like explaination of what they do and how they are used! Also what are IDU's?
cheers

ed
0

Featured Post

Connect further...control easier

With the ATEN CE624, you can now enjoy a high-quality visual experience powered by HDBaseT technology and the convenience of a single Cat6 cable to transmit uncompressed video with zero latency and multi-streaming for dual-view applications where remote access is required.

Question has a verified solution.

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

Load balancing is the method of dividing the total amount of work performed by one computer between two or more computers. Its aim is to get more work done in the same amount of time, ensuring that all the users get served faster.
For many of us, the  holiday season kindles the natural urge to give back to our friends, family members and communities. While it's easy for friends to notice the impact of such deeds, understanding the contributions of businesses and enterprises i…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
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…

740 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