* Ignore any (ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME) errors due to ip
  fragment reassembly timeouts.
* Make sure that transport's pmtu is not set to a value lower than
  SCTP_DEFAULT_MINSEGMENT even when the value reported by
  (ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED) error is lower.