Re: [atlas] Strange and undocumented (?) result in traceroute JSON output

17 Jul 2013


      On 7/17/13 9:17 AM, Stephane Bortzmeyer wrote:
...
Measurement #1013405 contains:
"result": [
           {
             "x": "*"
           },
           {
             "late": 20,
             "ttl": 61,
             "from": "88.79.15.141",
             "size": 96
           },
           {
             "x": "*"
           },
           {
             "x": "*"
           }
While "late" is documented
<https://atlas.ripe.net/doc/data_struct#v4400_traceroute>, the lack of
"rtt" field is not and crashes tools like json2traceroute.py.
tools like json2traceroute.py which aim to reconstruct the routing 
vector should be aware of responses which arrive out of order; packets 
which are 'late' or show 'ittl' in the result require special attention 
because the 'from' address listed verly likely is from a router at a 
different hop.
json2traceroute.py could simply ignore the 'strange' results by changing 
the lines

    ...
    else:
             rtt.append(hr["rtt"])
             hopfrom = hr["from"]
             ...

to

    ...
    elif (not "late" in hr) and (not "ittl" in hr):
             rtt.append(hr["rtt"])
             hopfrom = hr["from"]
             ...


-- Rene

Re: [atlas] Strange and undocumented (?) result in traceroute JSON output

Rene Wilhelm