Optimal MTU value


Many users complain that some websites do not open, and usual suggestion
is to change the MTU values in modem.
Applications are also recommended for trying different values.
tcp/ip optimizer from speedguide.net.

Now the following is another method for MTU selection.

General instruction for finding your optimal MTU size

Go to Start and select Run.
Set router to MTU 1500 to start with.
Start RUN
Type in cmd (Windows 2000/XP/Vista/7) or
command (Windows 98/ME) into the box .
Hit the enter key or click OK
At the DOS prompt,
type in ping bbc.co.uk -f -l 1492 ( *or your choice of site)
and hit the Enter key.
If you get the response "Packet needs to be fragmented but DF set",
lower the size the packet in increments of +/-10 (e.g. 1472, 1462, 1440, 1400)
until you have a packet size that does not fragment.

Now increase the packet size from this number in small increments until you
find the largest size that does not fragment.
Add 28 to that number (IP/ICMP headers) to get the optimal MTU setting.
For example, if the largest packet size from ping tests is 1462, add 28 to 1462
to get a total of 1490 which is the optimal MTU setting and can be put
in your router's settings
Hope this helps some of you!?

Source : Netgear site.


Computer Addict
Very useful. :)You can also try MTU values as 1480, 1490 etc. It should work, but if you are still facing problems with some sites, you can try using Opera Turbo. It can open such sites.


I have seen a very strange problem in some of bsnl broadband modem (like ZTE) in always on router mode. The problem is that if u configure the modem in always on mode, only google sites (google, gmail, orkut, youtube) will be opened.But other site will not be opened. I have tried lot more to solve this problem al last the divisional Eng of broadband Mr Maynak Gupta told me me how to solve the problem. We need to change the MTU value . U will find the default mtu value is 1492 during configure of modem. call me to know the correct value my number is 9903xxxxxxx[/color]

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ZTE Adsl modem831aii usually based on Siemens C2110 board. ( wifi modem Teracom AR800V3 etc )ZTEZXDSL WIFI router531B ( issued in India ) same as WA3002-g4 beetel 450BXI DNA A212-I etc.Same hardware board and wireless board. ( see sticky post wa3002_g4 quick reference ).2. IF the BSNL engineer has suggested one MTU value, it has to be common to all units of ZTE ZXDSL531B,and you could kindly post the information here. Thanks.


Computer Addict
IF the BSNL engineer has suggested one MTU value, it has to be common to all units of ZTE ZXDSL531B,
and you could kindly post the information here. Thanks.

To me ? Got the values confirmed by a few user who tried them in other forum.