UDP action for packet too big message - TCP-IP

This is a discussion on UDP action for packet too big message - TCP-IP ; Hi, I have a query regarding the ICMP packet too big message. When we get a ICMP packet too big message for a UDP packet, what is the action taken?? Also do we need to inform about the change in ...

+ Reply to Thread
Results 1 to 2 of 2

Thread: UDP action for packet too big message

  1. UDP action for packet too big message

    Hi,

    I have a query regarding the ICMP packet too big message.
    When we get a ICMP packet too big message for a UDP packet, what is the
    action taken??
    Also do we need to inform about the change in MTU to the TCP.
    Could some one answer this query ASAP.

    Thank you
    Shobha


  2. Re: UDP action for packet too big message


    shobha_099@yahoo.com wrote:
    > Hi,
    >
    > I have a query regarding the ICMP packet too big message.
    > When we get a ICMP packet too big message for a UDP packet, what is the
    > action taken??


    It's not clear what you're asking. Are you asking what an application
    should do or what the kernel shoul do? The kernel should inform the
    application. An application should send smaller datagrams or stop
    settings the DF bit.

    What is the "we"?

    > Also do we need to inform about the change in MTU to the TCP.


    You could, but I'm not so sure it's a good idea. (Assuming there is a
    TCP connection to the same destination.) I believe some operating
    systems keep a table of each destination IP and its current best
    estimate of the path MTU. Some redetermine the MTU for each TCP
    connection as if they had no idea from the beginning. Google for 'path
    mtu discovery' or 'pmtu discovery'.

    > Could some one answer this query ASAP.


    If you need a quick answer, put some effort into asking a detailed
    question including at a minimum what you're trying to do (write an
    application? write a TCP/IP stack?). That will save many back-and-forth
    rounds and teeth pulling just to get at what your actual question
    really is.

    DS


+ Reply to Thread