why we cannot able to change MTU > 1500. - Linux

This is a discussion on why we cannot able to change MTU > 1500. - Linux ; hi frnds, this is sathiyadev.t here.i have a doute that, why we cont able to change the MTU of networking card more than 1500. can any one pls explain about this aspect. if it is possible to change the MTU ...

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Thread: why we cannot able to change MTU > 1500.

  1. why we cannot able to change MTU > 1500.

    hi frnds,

    this is sathiyadev.t here.i have a doute that, why we cont
    able to change the MTU of networking card more than 1500. can any one
    pls explain about this aspect.

    if it is possible to change the MTU > !500 pls
    guide me regarding changing the MTU.

    -sathiyadev.


  2. Re: why we cannot able to change MTU > 1500.

    On 2 Jan 2007 04:33:46 -0800, sathiya wrote:

    > if it is possible to change the MTU > !500 pls
    > guide me regarding changing the MTU.


    No, you can't do that, becasue 1500 bytes is the maximum allowed payload
    for 10/100 Ethernet. If you use Gigabit then you can have a larger MTU.

    Why do you think you need this?


    --
    -| Bob Hauck
    -| Hooray for San Fancisco values!
    -| http://www.haucks.org/

  3. Re: why we cannot able to change MTU > 1500.

    "sathiya" writes:

    > hi frnds,
    >
    > this is sathiyadev.t here.i have a doute that, why we cont
    > able to change the MTU of networking card more than 1500. can any one
    > pls explain about this aspect.


    The MTU of Ethernet is specified to be 1500. If you somehow managed
    to create a larger frame, it wouldn't work with many Ethernet cards,
    so most cards won't let you do it. There are a few 100Mbps Ethernet
    cards that allow MTU > 1500, but enabling this without being sure the
    other end is capable of receiving such frames is unwise. Gigabit
    Ethernet allows larger frames as a standard.

    --
    Måns Rullgård
    mru@inprovide.com

  4. Re: why we cannot able to change MTU > 1500.

    On Tue, 02 Jan 2007 14:14:20 +0000 M?ns Rullg?rd wrote:
    | "sathiya" writes:
    |
    |> hi frnds,
    |>
    |> this is sathiyadev.t here.i have a doute that, why we cont
    |> able to change the MTU of networking card more than 1500. can any one
    |> pls explain about this aspect.
    |
    | The MTU of Ethernet is specified to be 1500. If you somehow managed
    | to create a larger frame, it wouldn't work with many Ethernet cards,
    | so most cards won't let you do it. There are a few 100Mbps Ethernet
    | cards that allow MTU > 1500, but enabling this without being sure the
    | other end is capable of receiving such frames is unwise. Gigabit
    | Ethernet allows larger frames as a standard.

    TCP/IP connections should establish the lesser MTU. Many UDP based
    protocols, like DNS, have their own limitations. If one of the cards
    is set to MTU>1500 it should still work fine for internetworking with
    other cards set to MTU<=1500. If the other end is MTU>1500, but the
    network in between can't handle it, there could be problems unless
    path MTU discovery is working (often not through firewalls/NATs).

    If you really need MTU>1500 for local traffic to squeeze every bit out
    of the LAN you can, you should avoid accessing anything else via the
    same interface. One card (MTU==1500) for regular net access and the
    other (MTU>1500) for the special need. Other options include going
    with multiple ethernets or gigabit ethernet if 100mbit at MTU==1500 is
    not enough.

    --
    |---------------------------------------/----------------------------------|
    | Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
    | first name lower case at ipal.net / spamtrap-2007-01-02-0910@ipal.net |
    |------------------------------------/-------------------------------------|

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