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paris-traceroute(1)


NAME

   paris-traceroute  -  An  advanced  implementation  of  traceroute which
   correctly handles load balancing servers among other things

DESCRIPTION

   We introduce Paris traceroute, a new  traceroute  to  respond  to  load
   balancing  routers.  Its  key innovation is to control the probe packet
   header fields in a manner that allows all probes towards a  destination
   to  follow the same path in the presence of per-flow load balancing. It
   also allows a user to distinguish between the presence of per-flow load
   balancing  and  per-packet  load  balancing.  Unfortunately, due to the
   random nature of per-packet load  balancing,  Paris  traceroute  cannot
   perfectly  enumerate  all  paths  in  all  situations.  But  it  can do
   considerably better than the classic traceroute, and it can flag  those
   instances  where  there  are  doubts.  The  problem,  if  one wishes to
   maintain certain header fields constant, is that traceroute still needs
   to  be  able  to  match  response  packets to their corresponding probe
   packets.

   Paris traceroute does this by varying header fields that are within the
   first  28  octets,  but are not used for load balancing. In the case of
   TCP probes, Paris traceroute varies the sequence number. In UDP probes,
   it  is  the  checksum  field. This requires manipulating the payload to
   yield the desired checksum, as packets with an incorrect  checksum  are
   liable to be discarded. In ICMP probes, it is a combination of the ICMP
   identifier and the sequence number. We carefully set the value  of  the
   ICMP  identifier  and  sequence  number  to  keep  constant  the header
   checksum of all probes to a destination. Figure 2  summarizes  the  IP,
   UDP,  and  ICMP  header fields that are used by load balancers, classic
   traceroute, and Paris traceroute. We include the  ICMP  type  field  as
   used  for  load  balancing,  even if we cannot verify it experimentally
   (routers only repond to one type of probes,  which  is  the  ICMP  echo
   request).  Our  experiments  with  UDP,  TCP,  and IPSec probes do give
   strong evidence that routers blindly use the first  four  octets  after
   the IP header combined with the IP fields to do load balancing.

OPTIONS

          -h,  --help                                   Displays  help and
          usage information

          -a<ALGORITHM>,    --algorithm=<ALGORITHM>       Choose     which
          algorithm to use. Default is "mda".

BUGS

   No known bugs. If any are found please feel free to email us.

AUTHOR

   Julian Cromarty (julian.cromarty@gmail.com)



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