This is our old Q&A Site. Please post any new questions and answers at

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?


ping -l 1472 -f

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

Ping statistics for 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

accept rate: 13%

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

permanent link

answered 05 Feb '14, 10:47

mrEEde's gravatar image

accept rate: 20%

Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 05 Feb '14, 09:58

question was seen: 4,129 times

last updated: 05 Feb '14, 10:47

p​o​w​e​r​e​d by O​S​Q​A