pls help about mtu setting again

kmedcalf at dessus.com kmedcalf at dessus.com
Wed Jun 23 14:42:58 CDT 2010


1472 is the maximum ICMP payload size for standard Ethernet.  1480 fails because, well, it is > 1472.

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>-----Original Message-----
>From: Deric Kwok [mailto:deric.kwok2000 at gmail.com]
>Sent: Wednesday, 23 June, 2010 12:53
>To: nanog list
>Subject: pls help about mtu setting again
>
>Hi
>
>Thank you for your reply about DSL mtu
>
>Now I have question about internet cable connection. ls it same as DSL?
>
>I tested it in my friend cable connection.
>
>1470 is fine but 1480 is problem. Why it needs header in cable connection
>also?
>
>C:\Documents and Settings\deric>ping yahoo.com -f -l 1470
>
>Pinging yahoo.com [98.137.149.56] with 1470 bytes of data:
>
>Reply from 98.137.149.56: bytes=1470 time=96ms TTL=50
>Reply from 98.137.149.56: bytes=1470 time=91ms TTL=50
>Reply from 98.137.149.56: bytes=1470 time=92ms TTL=50
>Reply from 98.137.149.56: bytes=1470 time=89ms TTL=50
>
>Ping statistics for 98.137.149.56:
>  Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
>Approximate round trip times in milli-seconds:
>  Minimum = 89ms, Maximum = 96ms, Average = 92ms
>
>C:\Documents and Settings\deric>ping yahoo.com -f -l 1480
>
>Pinging yahoo.com [98.137.149.56] with 1480 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 98.137.149.56:
>  Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
>
>Thank you for your help








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