An interim solution to the Path MTU discovery problem for IPsec gateways

Document Type Expired Internet-Draft (individual)
Author Michael Richardson 
Last updated 2004-07-19
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


Path MTU discovery depends upon proper respect for the Don't Fragment (DF) bit. IPsec gateways often present an Maximum Transmission Unit (MTU) constraint, and therefore must send ICMP Fragment Needed messages when the DF bit is set. This document proposes to ignore it in certain cases.


Michael Richardson (

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