October 19, 2012

Set MTU Size On Your Linksys Router Settings

If you are experiencing problem with your Linksys Cisco router that randomly disconnected and intermittent connection this information might help you solve the issue. Setting the correct MTU (Maximum Transmission Unit) size on your router help you avoid packet loss and connection drops is a way to troubleshoot your router connection behavior. 

Linksys MTU Size

How to Determine Correct MTU Size


1. Do a ping test on a specific url web address or to anothercomputer.

Follow this format to do a ping test on Command Prompt:

ping yahoo.com –f –l 1472

Linksys MTU Size Settings


where:
  • yahoo.com = is your web address url
  • -f = to make sure that when you ping a certain address, it will not fragment the packet sent or received.
  • -l = packet size switch command to help you determine the best MTU on your network
  • 1472 = the packet size (value) you will use for testing. In testing packet size value start from 1472, work way down by decrease its value by 10 so your next testing packet size value will be 1462 and so on.

Note: To access Command Prompt in Windows Xp just click on Start >Run then cmd and hit Enter or click Ok. For Windows 7 go here or just press Windows key + R then type cmd and hit enter.

2. After typing ping yahoo.com –f –l 1472 on the Command Prompt, hit Enter.

3. Take note on the ping results (see image below) if you get “Packet needs to be fragmented but DF set.” means it is not the exact packet size for you network.
Linksys MTU Size Settings

4. Try another packet size value work way down by decreasing the packet size value that I mentioned above. (In my image above, my next try is ping yahoo.com –f –l 1462) 

5. Bingo, since (4) replies received:  This means that the packet size entered is either within or the actual MTU size used within your network.

6. Lastly, to get the correct MTU add 28 to the packet size value where you get (4) replies. (example: 1462+28 making it 1490) 

Next is setting the correct MTU to your Linksys router:

7. Login to you router web based setup, open you web browser type 192.168.1.1 then type your router username and password.

8. On you router setup page look for the option where you can set your MTU size. (on my WRT54G2 router it is located in Setup tab)

9. Set it to Manual then type the result on step 1- 6. (on this example the correct MTU result is 1490).(source)

You may read this post Limit Bandwidth on Linksys Router WRT54G2 or this How To Setup Linksys WRT54G2 Router.

As I am using Linksys WRT54G2 router I experienced the problem of always disconnecting status, tried some suggested workaround at Linkys community forum but what works for me is the correct MTU settings.

2 comments:

  1. incorrect parameter -f

    through windows 7 64 bits.

    ReplyDelete
    Replies
    1. you may try using "/" instead of - , to solve the incorrect parameter error

      Delete