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)

www.paris-traceroute.net                          8th June 2012                              paris-traceroute(1)