speedguide.net/analyzer.php , Not showing correct MTU ???

[speedms]

Hi all, :)

I connect to internet through a PPPoE DSL connection via ADSL router.

Problem is, when I check my connection in http://www.speedguide.net/analyzer.php, It

shows my MTU = 1452 and MSS = 1412 :confused:

Here is a copy of that webpage :


TCP options string = 020405840103030001010402

MTU = 1452
MTU is not fully optimized for broadband. Consider increasing your MTU to 1500 for better

throughput. If you are using a router, it could be limiting your MTU regardless of Registry

settings.

MSS = 1412
MSS is not optimized for broadband. Consider increasing your MTU value.

Default TCP Receive Window (RWIN) = 17424

RWIN Scaling (RFC1323) = 0 bits

Unscaled TCP Receive Window = 17424
For optimum performance, consider changing RWIN to a multiple of MSS.
Other RWIN values that might work well with your current MTU/MSS:
519616 (MSS x 46 * scale factor of 8)
259808 (MSS x 46 * scale factor of 4)
129904 (MSS x 46 * scale factor of 2)
64952 (MSS x 46)

bandwidth * delay product (Note this is not a speed test):

Your TCP Window limits you to: 696.96 kbps (87.12 KBytes/s) @ 200ms
Your TCP Window limits you to: 278.784 kbps (34.848 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.

MTU Discovery (RFC1191) = ON

Time to live left = 49 hops
TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349) = 00000000 (0)


But when I ping :


D:\Documents and Settings\AdminXP>ping speedguide.net -f -l 1464

Pinging speedguide.net [63.217.30.70] with 1464 bytes of data:

Reply from 63.217.30.70: bytes=1464 time=462ms TTL=251
Reply from 63.217.30.70: bytes=1464 time=463ms TTL=251
Reply from 63.217.30.70: bytes=1464 time=457ms TTL=251
Reply from 63.217.30.70: bytes=1464 time=461ms TTL=251

Ping statistics for 63.217.30.70:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 457ms, Maximum = 463ms, Average = 460ms

D:\Documents and Settings\AdminXP>ping speedguide.net -f -l 1465

Pinging speedguide.net [63.217.30.70] with 1465 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 63.217.30.70:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),


SG TCP Optimizer MTU calculator :

Pinging [63.217.30.70] with 40 bytes ->bytes=40 time=426ms TTL=251
Pinging [63.217.30.70] with 750 bytes ->bytes=750 time=442ms TTL=251
Pinging [63.217.30.70] with 1125 bytes ->bytes=1125 time=455ms TTL=251
Pinging [63.217.30.70] with 1312 bytes ->bytes=1312 time=458ms TTL=251
Pinging [63.217.30.70] with 1406 bytes ->bytes=1406 time=462ms TTL=251
Pinging [63.217.30.70] with 1453 bytes ->bytes=1453 time=463ms TTL=251
Pinging [63.217.30.70] with 1476 bytes -> ..fragmented
Pinging [63.217.30.70] with 1465 bytes -> ..fragmented
Pinging [63.217.30.70] with 1459 bytes ->bytes=1459 time=460ms TTL=251
Pinging [63.217.30.70] with 1462 bytes ->bytes=1462 time=463ms TTL=251
Pinging [63.217.30.70] with 1463 bytes ->bytes=1463 time=462ms TTL=251
Pinging [63.217.30.70] with 1464 bytes ->bytes=1464 time=462ms TTL=251
The largest possible non-fragmented packet is 1464 (1492 - 28 ICMP & IP headers).
You can set your MTU to 1492


From the above, results it is evident, MTU = 1492.

But, why http://www.speedguide.net/analyzer.php is showing MTU = 1452. :confused: