On 2013-12-24 18:55, Jeroen Massar wrote:
On 2013-12-25 00:16, Sam Moats wrote:
Hello Nanog community,
I would like to enlist your help with understanding this latency I'm
seeing.
You are likely seeing the effects of asymmetric routing.
That's what I was thinking to.
[..]
Tracing route to xxx.yyy.ie [193.1.x.x]
www.heanet.ie by chance? :)
Yes they were the owners of the IP I used for the example case and the
heanet folks are actually totally awesome :-)
Though you could use for instance:
http://planchet.heanet.ie/toolkit/gui/reverse_traceroute.cgi
to do a reverse traceroute, do make sure you force your connectivity
to
IPv4 as that host will do IPv6 too. (locally nullrouting the
destination
/128 is the trick I use for 'disabling' IPv6 temporarily).
Otherwise the HEANET folks are extremely helpful and clued in, you
can
always ask them for help with issues. It is the end-of-year though
and
those Irish folks have lots of really good whiskey, Guinness thus you
might have to be patient till the new year.
Also you'd be amazed how many network issues can be solved with a bunch
of IT folks and an ample supply of Guinness
Alternatively, you could use a tool like 'tracepath' or 'mtr' as
those
reports multiple answers to a response and also check for the TTL on
the
return packets.
Greets,
Jeroen
Thanks, this isn't affecting my service now I've worked around it so
it's more a curiosity than anything. It seems really odd to me that the
same L3 edge router would route the ICMP unreachable back to me via
different paths based on the final destination IP of the of the ICMP
echo packet.
Well its Christmas eve here and the customers are happy so Guinness
seems like the best approach now :-)
Thanks and have a good Holiday,
Sam Moats
