Message ID
6
Message
Detected MTU is a known standard
Description
An MTU is in use other than 1500 bytes, and corresponds to a well-known standard.
Recommendations
No action required.
Explanation
MTU, or maximum transmission unit, is also known as link MTU. Measured in bytes, it's the maximum packet size that can be sent in one piece over a hop without being fragmented. It differs from path MTU (PMTU) which is the minimum MTU of the hops in a path. In the presence of packet loss the path MTU discovery process can generate an underestimate for the MTU. One way to verify the discovered MTU is to re-run the test a couple times to see if the result is consistent. That said, the fact that the discovered MTU is associated with a known standard suggests that it is not an accidental underestimate.
Possible secondary messages
  • 576 bytes corresponds to ISDN
  • 1006 bytes corresponds to SLIP
  • 1476 bytes corresponds to a GRE Tunnel or other encapsulation mechanism
  • 1492 bytes corresponds to IEEE 802.3/802.2, PPPoE
Related topics
Maximum Transmission Unit (MTU)
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