I did a DOS command of ping -f -l [MTU value] [isp gateway address] and to my amazement i found that the largest packet i can send is only 248 (bytes - i think the unit is) and i'm supposed to be on Mumbai's (India) best known and popular broadband connection.
Any explanations or help forthcoming on this
Should i reset my MTU values or .....
Is there a problem if an MTU value is too large im comparison with the size of ther packet that can get thru unfragmented??
My ISP's website is http://www.powersurrfer.net
My MTU test results - wierd and shocking
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perfection2003
rmrucker
Thanks for a quick reply
The above results (in the earlier post) are when i pinged the IP address but when i pinged the gateway i found that the max MTU supported (without fragmentation message) was 1472 with a TTLof 225. [Do you think i'm on pppoe whatever that means ? - a little knowledge is a dangerous thing)
Should i make any changes based on these results?
What does it mean and should i change my TTL.
Why the huge difference when i ping the IPSP address and the gateway address??
Thanks for a quick reply
The above results (in the earlier post) are when i pinged the IP address but when i pinged the gateway i found that the max MTU supported (without fragmentation message) was 1472 with a TTLof 225. [Do you think i'm on pppoe whatever that means ? - a little knowledge is a dangerous thing)
Should i make any changes based on these results?
What does it mean and should i change my TTL.
Why the huge difference when i ping the IPSP address and the gateway address??
1472 would be the highest packet size. It's actually your MSS value that you're tring to determine using the ping method. MSS is the Maxium amount of usefull data in each packet. Each packet contains a 40 byte header so if your MTU is 1500 them MSS is 1460.
Even though you can ping at 1472 the maxium MTU can be is 1500.
Even though you can ping at 1472 the maxium MTU can be is 1500.
"A never ending quest for knowledge as with knowledge comes wisdom"
Main System running Windows XP Pro: Intel Celeron 2.4 Ghz, 1 Gig Ram, 2 80 gig WD 7200 rpm HD's, Radeon 9200 Pro, Envision EN9110 19" LCD Display, HP 9500 CD-RW, D-Link DFE-530TX+ PCI Adapter, D-Link DI-704P Router, Motorola SB5100 Cable Modem with Cox HSI
Main System running Windows XP Pro: Intel Celeron 2.4 Ghz, 1 Gig Ram, 2 80 gig WD 7200 rpm HD's, Radeon 9200 Pro, Envision EN9110 19" LCD Display, HP 9500 CD-RW, D-Link DFE-530TX+ PCI Adapter, D-Link DI-704P Router, Motorola SB5100 Cable Modem with Cox HSI
Can you ping something beyond your gateway and get a 1472 buffer packet through? For example, try pinging http://www.speedguide.net.
If you can ping your gateway with a full size packet (1472), then at least your computer and your connection to your gateway is set up correctly. Something between your gateway and your ISP may have a problem...
The TTL value is essentially unimportant as long as you don't set it too low. Either 64 or 128 are fine.
Given the fact that you can ping with a 1472 size buffer, I would guess this is not PPPoE. PPPoE generally adds an 8 byte wrapper to the packets, so I would suspect a maximum buffer size of 1464 for a ping packet if you were on PPPoE.
However, you can usually tell if you are on PPPoE if you check the Network Properties Control Panel Screen -- especially if third-party PPPoE programs are being used (Enternet, Access Manager, WinPoET, etc.).
For what it is worth, I am able to ping the site (eh, spelled a little differently) with full size packets:
Pinging hasdc.powersurfer.net [202.68.128.70] with 1472 bytes of data:
Reply from 202.68.128.70: bytes=1472 time=427ms TTL=237
Reply from 202.68.128.70: bytes=1472 time=474ms TTL=237
Reply from 202.68.128.70: bytes=1472 time=466ms TTL=237
Reply from 202.68.128.70: bytes=1472 time=605ms TTL=237
Ping statistics for 202.68.128.70:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 427ms, Maximum = 605ms, Average = 493ms
...So the site is responding normally.
If you can ping your gateway with a full size packet (1472), then at least your computer and your connection to your gateway is set up correctly. Something between your gateway and your ISP may have a problem...
The TTL value is essentially unimportant as long as you don't set it too low. Either 64 or 128 are fine.
Given the fact that you can ping with a 1472 size buffer, I would guess this is not PPPoE. PPPoE generally adds an 8 byte wrapper to the packets, so I would suspect a maximum buffer size of 1464 for a ping packet if you were on PPPoE.
However, you can usually tell if you are on PPPoE if you check the Network Properties Control Panel Screen -- especially if third-party PPPoE programs are being used (Enternet, Access Manager, WinPoET, etc.).
For what it is worth, I am able to ping the site (eh, spelled a little differently) with full size packets:
Pinging hasdc.powersurfer.net [202.68.128.70] with 1472 bytes of data:
Reply from 202.68.128.70: bytes=1472 time=427ms TTL=237
Reply from 202.68.128.70: bytes=1472 time=474ms TTL=237
Reply from 202.68.128.70: bytes=1472 time=466ms TTL=237
Reply from 202.68.128.70: bytes=1472 time=605ms TTL=237
Ping statistics for 202.68.128.70:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 427ms, Maximum = 605ms, Average = 493ms
...So the site is responding normally.