question on TTL in the IP header - TCP-IP

This is a discussion on question on TTL in the IP header - TCP-IP ; My understanding is that the TTL filed (hop count), in the IP header, is useful during network instability (reconvergence of routing protocol after a topology change: a network element fails or comes up). My question is how useful is that ...

+ Reply to Thread
Results 1 to 3 of 3

Thread: question on TTL in the IP header

  1. question on TTL in the IP header


    My understanding is that the TTL filed (hop count), in the IP header, is
    useful during network instability (reconvergence of routing protocol
    after a topology change: a network element fails or comes up).

    My question is how useful is that filed. I.e. if there were not the TTL
    field, what would be the impact on the network ?

    all comments are very welcome.
    Thank you.
    AL

  2. Re: question on TTL in the IP header

    In article ,
    Ali wrote:

    > My question is how useful is that filed. I.e. if there were not the TTL
    > field, what would be the impact on the network ?


    When there are routing loops, the links involved would fill up with
    packets that keep going round and round, totally bogging down those
    connections.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  3. Re: question on TTL in the IP header

    Ali wrote:

    >
    > My understanding is that the TTL filed (hop count), in the IP header,
    > is useful during network instability (reconvergence of routing
    > protocol after a topology change: a network element fails or comes
    > up).
    >
    > My question is how useful is that filed. I.e. if there were not the
    > TTL field, what would be the impact on the network ?
    >
    > all comments are very welcome.



    Barry already gave you an example. But just to drive home the point,
    Ethernet frames lack the TTL field. So if you create a layer two loop,
    you will get 12.5MBps (10Mbps) throughput on your 10Mb switches!

    Since the frame will never die, it will just go around and around and
    around the loop.


    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not be able to
    reply to emails sent to my account. Please post a followup instead.
    ************************************************** ******************

+ Reply to Thread