Re: Linux 2.4 - Writing packets with IP_DF set with packets bigger than pmtu

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Raghu,

I wouldn't want to be insulting to those working hard on Linux, but you are correct that the PMTU implementation insists on attempting to utilize PMTU information or apply PMTU techniques to datagrams that shouldn't be touched by PMTU (NFS for example).

If you implement your own ARP functionality, you'll need to use libpcap to observe the response from the remote host when attempting to determine it's hardware address. However, that won'd actually solve your problem. You can't send an Ethernet frame larger than MTU, it just won't work.

I'd suggest temporarily turning off your PMTU functionality and/or patching your linux Kernel with some functionality to properly preserve DF on a packet larger than MTU.

• -Jeff
• --On Saturday, March 08, 2003 20:15:03 +0000 "rreddy@psc.edu" <rreddy@psc.edu> wrote:
  >
  > Hi,
  >
  > We want to write packets that are bigger than path MTU (pmtu that is
  
• -- http://www.snort.org/~jeff (pgp key available) "Perhaps the greatest responsibility in promoting peace is that of protecting it."
• - Me

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