[Asterisk-Users] Re: How is Teliax ?

[Rich Adamson]

> I would not ride on a tracert too much. We use Teliax also and our ISP that
> we have at the data center switched there backbones around the same time
> Teliax where doing there upgrades. 

For those that have not analyzed how tracert actually works, you can't 
depend on its output to give you factual evidence as to where delays 
occur in an end-to-end path. Each step through the tracert process does 
nothing more then issue an icmp echo request, measuring the response 
time and displaying it. When a high value is reported (eg, at router #10 
for example), there is no way to know (factually) whether that high 
response was from that particular device (#10) or one of the routers 
prior to that address (eg, #3, #5, or #9). All you really know is that 
at the time the icmp was sent, the response was delayed for some reason, 
and it could have been any of the devices prior to the specific one that 
  you thought was the issue.

> We started seeing some call issues and when we did a tracert we started
> getting some dropped tracert responses on our ISP new backbone(Time Warner)
> when our ISP investigated it Time Warner responded that tracerts get a VERY
> low priority on their routers and that is why we where seeing these drops. 

The "low priority" comment is one that was started by Cisco folks many 
years ago when router processors were taxed much heavier then current 
day products. Back then, Cisco IOS firmware prioritized various events 
and icmp's were (and still are) low priority events. However, since then 
the processor speeds have significantly increased and off-loading of 
many routing events to card-level processors have occurred. The 
processing of icmp traffic is seldom (if ever) impacted in any 
measurable way in products manufactured in the last five to ten years.

> Once Teliax did whatever their last change was fixed all of our issue and we
> have not see any call issue in the last 2-3 weeks. Still see drops on the
> traces. I would look more at the latency and for dropped packets if you do a
> continues ping with setting the size to something other then default and see
> if you get any dropped packets or high latency.

Right on!