Question about Siemens SpeedStream Modem (4100) (SS4100)

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M t u

What the **** is mtu

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In computer networking, the term Maximum Transmission Unit (MTU) refers to the size (in bytes) of the largest packet that a given layer of a communications protocol can pass onwards.
MTU parameters usually appear in association with a communications interface (NIC, serial port, etc.).
The MTU may be fixed by standards (as is the case with Ethernet) or decided at connect time (as is usually the case with point-to-point serial links).
A higher MTU brings higher bandwidth efficiency. However, large packets can block a slow interface for some time, increasing the lag on other packets. For example, a 1,500-byte packet, the largest allowed by Ethernet (and most of the Internet), would block up a 14.4k modem for about one second.
The default MTU on a PPPoE connection is 1,492. The default MTU for a DHCP or PPPoA connection is 1,500.
Increasing the MTU size beyond these levels is possible on a client computer, but not recommended, because the MTU size on the outbound connection to the ISP will nullify any potential gains from a larger MTU.

Posted on Apr 21, 2008

  • Van Estella
    Van Estella Apr 21, 2008

    Finding the Correct MTU
    To find the correct MTU for your configuration you must run a simple
    DOS Ping test. You will simply send out ping requests and progressively
    lower your packet size until the packet no longer needs to be
    fragmented. Please reference the following steps:

    The command for this ping test is ping www.urlname.com -f -l xxxx.
    You can use any well known, pingable domain like ping www.google.com -f -l xxxx in place of www.urlname.com for the test.
    •There is a single space between each command.
    •"-l" is a lower case letter L, not the number one.
    •The xxxx are the test packet size. (like 1472)
    At the DOS Prompt type in ping www.google.com -f -l 1472 and hit Enter. Notice that the packet needs to be fragmented. (you get a message "packet needs to be fragmented but DF set")
    Drop the test packet size down (10 or 12 bytes) and test again. If the packet still needs to be fragmented, drop the test packet size down more and test again until your reach a packet size that does not fragment.Once you have a test packet that is not fragmented increase your packet
    size in small increments and retest until you find the largest possible
    packet that doesn't fragment. Take the maximum packet size from the ping test and add 28. You add 28 bytes because 20 bytes are reserved for the IP header and 8 bytes must be allocated for the ICMP Echo Request header. Remember: You must add 28 to your results from the ping test!
    An example:
    1440 Max packet size from Ping Test
    + 28 IP and ICMP headers
    1468 your optimum MTU setting

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1 Answer

How do i change my mtu setting?


This WEB site gives you details on adjusting MTU settings for your version of Windows.
http://help.expedient.com/broadband/mtu.shtml

Apr 14, 2011 | Zoom 5241 Modem

1 Answer

We are having trouble getting xbox live we have a wirless thompson TG782T it says we nead to change the MTU setting.Bigpond and telsta have been no help and say that we shouldnt have to change the Mtu...


Set your console to have a static IP address.
Make it something like 192.168.1.84 (where 84 can be anything from 2 to 250, so long as it is not the same as any other device)
Subnet mask, 255.255.255.0
Default gateway 192.168.1.254
DNS 192.168.1.254

MTU 1500.

If this doesn't fix it, try
10.0.0.150
255.255.255.0
gateway 10.0.0.138
DNS 10.0.0.138
MTU 1500


~KenjiFox

Jan 07, 2011 | Modems

1 Answer

Isn't there an internet site where i can change my MTU settings on SURBboard sb5101, i need the settings to be at least 1364


It is not possible to change the MTU settings for cable modem... MTU settings are applicable only for ADSL connections like AtT or Verizon...

Dec 07, 2010 | Arris SURFboard® SB5101 Cable Modem

1 Answer

I want to change the MTU setting to 1364


Cablemodems are bridge devices the MTU setting you are looking for would be in your OS or router (easier to set on a router though).
checkout http://help.expedient.com/broadband/mtu.shtml

Oct 15, 2010 | Arris SURFboard SB4200 Modem

1 Answer

What is the mtu and can it be changed?


To change the mtu you have to login to the web page of the modem and from there you will have an option to change the mtu. The default will be 1492 , change that to 1400 or 1358 for reliable communication with the x-box.

Dec 06, 2009 | Efficient Networks SpeedStream 5360...

1 Answer

MTU settings


where do i go to change the mtu settin on a comtrend ct-5364a

Sep 11, 2009 | Modems

1 Answer

How do you change the mtu settings on a sb4200


Hi,

Try to access the Web interface of your router. Access http://192.168.100.1 and look for MTU. I think it is set to 1500 by default.

Jul 06, 2009 | Arris SURFboard SB4200 Modem

1 Answer

Bestdata cmx300v2 mtu setting is too low


My MTU is at 1500 and I get the same message. I don't think XBL is up yet. It is under repair.

Jun 16, 2009 | Modems

3 Answers

Changing the MTU setting


Log into modem using 192.168.2.1 in your browser and go to modem utility through browser.

May 18, 2008 | Siemens SpeedStream Modem (4100) (SS4100)

1 Answer

Mtu


The modem (westell wirespeed)you have does not have is a old modem... that does have options to set the mtu settings. You need to change the modem. By the way why you need to set the MTU settings,.

Apr 07, 2007 | Westell Wirespeed LiteLine 6110 Modem

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