Thanks guys. Sorry for the noise... Derek On 9/26/2012 9:11 PM, Jay Ashworth wrote:
From: "Derek Ivey" <derek@derekivey.com> I'm at home now. I also have Verizon FiOS and believe I am seeing the same thing our client saw. So you guys are saying that the response times in traceroutes might not always be accurate because routers prioritize ICMP messages. Does that mean values from MTR aren't accurate? I fired up MTR and took 2 screenshots (http://imgur.com/a/RDyXO). What do you guys think? Most of the time the ping times seem fairly low, however I occasionally see these spikes. It seems sporadic... To recap, traceroute, mtr, and similar utilities work by talking to each succesive router along a path. Because this is so, and because Any Given Router may be too busy to deal with such packets in favor of "real" traffic (most routers handle data packets on the line cards, while they may have to expend actual CPU on things like ICMP), it's possible for a path with
----- Original Message ----- perfect connectivity to show some intermediate hops completely missing -- No Reply At All, you might say -- to diagnostic tools.
The traces you show look pretty decent; I've seen much worse on links with fine interactive shell session response. The time you have to worry is when one router *and everything past it* shows packet loss of roughly the same amount, or when ping times jump markedly at a given spot (by which I mean, say, from 32 to 800ms, rather than from 32 to 125).
The short version, though, which most people are are being uncharacteristically too nice to say (:-) is that this is still a tier 1 problem, and NANOG is generally tier 3 or 4. :-)
You're welcome to take the issue up over on outages@outages.org, if you like...
Cheers, -- jra