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MTU question

0

If a router's WAN interface is configured for an MTU of 1500, I should not be able to send an non-fragmented packet over 1500 outside, but it gets through.

where does it find room for another 14 bytes?

Thanks

http://www.cloudshark.org/captures/a00ef83e9e99

ping 8.8.8.8 -l 1472 -f

Pinging 8.8.8.8 with 1472 bytes of data:
Reply from 8.8.8.8: bytes=64 (sent 1472) time=43ms TTL=46
Reply from 8.8.8.8: bytes=64 (sent 1472) time=34ms TTL=46
Reply from 8.8.8.8: bytes=64 (sent 1472) time=35ms TTL=46
Reply from 8.8.8.8: bytes=64 (sent 1472) time=34ms TTL=46

Ping statistics for 8.8.8.8: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 34ms, Maximum = 43ms, Average = 36ms

asked 05 Feb '14, 09:58

net_tech's gravatar image

net_tech
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accept rate: 13%

One Answer:

2

MTU size is the largest ip.len that is getting through. For ethernet you need to add 14 bytes header alt text

answered 05 Feb '14, 10:47

mrEEde's gravatar image

mrEEde
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accept rate: 20%