Anyone from Verizon/TATA on here? Possible Packet Loss

Derek Ivey derek at derekivey.com
Thu Sep 27 00:45:54 UTC 2012


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...

My boss also has FiOS and he is seeing the same thing. Pages load quick 
most of the time and sometimes take awhile to load.

Thanks,
Derek

On 9/26/2012 3:19 PM, Pellitteri Alexis wrote:
> That router might be experiencing a high CPU load, thus not being able 
> to reply ICMP on a timely manner or maybe QoS policies are influencing 
> depending on the kind of traffic the router deals with.
>
> If packets are only being delayed/lost on that segment, I would start 
> my analysis there.
>
>
> On 09/26/2012 04:02 PM, Jo Rhett wrote:
>
> Many (most?) routers deprioritize ICMP meesages. Direct pings against 
> the router are not informative re transit failures.
>
> On Sep 26, 2012, at 11:37 AM, Derek Ivey wrote:
>
>> After some further troubleshooting, I believe I have narrowed down 
>> the issue to one of Verizon's routers (130.81.28.255).
>>
>> ping 130.81.28.255 repeat 100
>> Type escape sequence to abort.
>> Sending 100, 100-byte ICMP Echos to 130.81.28.255, timeout is 2 seconds:
>> ?!!!!!!!!?!!!!!!!?!!!!!!!!?!!!!!!!!!!!!!!!?!!!!!!!!!!!!!!?!!!!!!!!!!!?
>> !!!!!!!!!!!!!!!!!!!!!!?!!!?!!!
>> Success rate is 91 percent (91/100), round-trip min/avg/max = 
>> 20/26/30 ms
>>
>> I had my client send me the output of the ping command (100 pings) 
>> and a trace route.
>>
>> Their 5th hop is 130.81.28.254 and one of the response times in their 
>> trace route was 175ms so the issue seems to be around there.
>>
>> I asked them to open a ticket with Verizon to take a look.
>>
>> Thanks,
>> Derek
>>
>> On Sep 26, 2012, at 1:54 PM, Derek Ivey <derek at derekivey.com> wrote:
>>
>>> Thanks guys. That was an informative read. I will do some more 
>>> troubleshooting.
>>>
>>> Derek
>>>
>>> On Sep 26, 2012, at 1:16 PM, Darius Jahandarie 
>>> <djahandarie at gmail.com> wrote:
>>>
>>>> On Wed, Sep 26, 2012 at 1:10 PM, Blake Dunlap <ikiris at gmail.com> 
>>>> wrote:
>>>>> This is not the proper way to interpret traceroute information. 
>>>>> Also, 3
>>>>> pings is not sufficient to determine levels of packet loss 
>>>>> statistically.
>>>>>
>>>>> I suggest searching the archives regarding traceroute, or googling 
>>>>> how to
>>>>> interpret them in regards to packet loss, as what you posted does not
>>>>> indicate what you think it does.
>>>> Agreed. Derek should read "A Practical Guide to (Correctly)
>>>> Troubleshooting with Traceroute":
>>>> http://www.nanog.org/meetings/nanog45/presentations/Sunday/RAS_traceroute_N45.pdf 
>>>>
>>>>
>>>> -- 
>>>> Darius Jahandarie
>
>




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