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/

"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

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.

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