Re: Help me make sense of these traceroutes please
From: Jeroen Massar <jeroen@massar.ch> To: sam@circlenet.us, nanog@nanog.org Subject: Re: Help me make sense of these traceroutes please
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.
. .. or the effect of passing traffic through NSA infrastructure. SCNR, #m
On Wed, Dec 25, 2013 at 8:03 AM, Martin Hotze <m.hotze@hotze.com> wrote:
On 2013-12-25 00:16, Sam Moats wrote:
...
You are likely seeing the effects of asymmetric routing. . .. or the effect of passing traffic through NSA infrastructure.
Ah... NSA. That's probably it. So much for my theory of a Router virtual chassis straddling the atlantic. or the extra kinetic energy carried by the overseas-bound packet took longer for the router to absorb and rebound with an ICMP. But in all seriousness --- what is probably happening here, is the result of extra "hops" that don't show up in traceroute. MPLS tunnels could well fit the bill. Other things to consider when latency seems sensitive to destination IP --- are preceding device in the traceroute might also have multiple links to the same device; with one link congested and some form of IP-based load sharing, that happens to be the toward-overseas link.
SCNR, #m
-- -JH
Start at slide 50: This is documented further by the following Nanog presentation. http://www.nanog.org/meetings/nanog47/presentations/Sunday/RAS_Traceroute_N4... -Marcus -----Original Message----- From: Jimmy Hess [mailto:mysidia@gmail.com] Sent: Wednesday, December 25, 2013 10:28 AM To: Martin Hotze Cc: nanog@nanog.org Subject: Re: Help me make sense of these traceroutes please On Wed, Dec 25, 2013 at 8:03 AM, Martin Hotze <m.hotze@hotze.com> wrote:
On 2013-12-25 00:16, Sam Moats wrote:
...
You are likely seeing the effects of asymmetric routing. . .. or the effect of passing traffic through NSA infrastructure.
Ah... NSA. That's probably it. So much for my theory of a Router virtual chassis straddling the atlantic. or the extra kinetic energy carried by the overseas-bound packet took longer for the router to absorb and rebound with an ICMP. But in all seriousness --- what is probably happening here, is the result of extra "hops" that don't show up in traceroute. MPLS tunnels could well fit the bill. Other things to consider when latency seems sensitive to destination IP --- are preceding device in the traceroute might also have multiple links to the same device; with one link congested and some form of IP-based load sharing, that happens to be the toward-overseas link.
SCNR, #m
-- -JH
Thanks to everyone who responded off list and on. Sam Moats On 2013-12-26 11:21, Josephson, Marcus wrote:
Start at slide 50:
This is documented further by the following Nanog presentation.
http://www.nanog.org/meetings/nanog47/presentations/Sunday/RAS_Traceroute_N4...
-Marcus
-----Original Message----- From: Jimmy Hess [mailto:mysidia@gmail.com] Sent: Wednesday, December 25, 2013 10:28 AM To: Martin Hotze Cc: nanog@nanog.org Subject: Re: Help me make sense of these traceroutes please
On Wed, Dec 25, 2013 at 8:03 AM, Martin Hotze <m.hotze@hotze.com> wrote:
On 2013-12-25 00:16, Sam Moats wrote:
...
You are likely seeing the effects of asymmetric routing. . .. or the effect of passing traffic through NSA infrastructure.
Ah... NSA. That's probably it. So much for my theory of a Router virtual chassis straddling the atlantic.
or the extra kinetic energy carried by the overseas-bound packet took longer for the router to absorb and rebound with an ICMP.
But in all seriousness --- what is probably happening here, is the result of extra "hops" that don't show up in traceroute. MPLS tunnels could well fit the bill.
Other things to consider when latency seems sensitive to destination IP --- are preceding device in the traceroute might also have multiple links to the same device; with one link congested and some form of IP-based load sharing, that happens to be the toward-overseas link.
SCNR, #m
-- -JH
participants (4)
-
Jimmy Hess -
Josephson, Marcus -
Martin Hotze -
Sam Moats