packet loss question

Phillip Lynn phillip.lynn at netwolves.com
Fri Jul 8 13:01:14 UTC 2016


On 07/07/2016 03:52 PM, Ken Chase wrote:
> No offence, but i swear that mtr should come with a license to use it. I get more
> questions from people accusing us of network issues with mtr in hand...
>
> You shoudlnt care that there's 80% packet loss in the middle of your route, unless
> you have actual traffic to lag-101.ear3.miami2.level3.net. I suspect you dont.
> (If you did, you'd have mtr'd to it directly of course.)
>
> As for your second trace, the sudden jump from 0% on 2nd last hop to 100% last
> hop packetloss seems like firewalling to me. (long discussion about the
> probabilities of getting 5 0%pl hops in a row and 100% on an unfirewalled
> endpoint elided. TL;DR: use more packets in your test -i 0.1 -c 100 thanks).
>
> If you have 0% packetloss to your target endpoint, is there an issue here?
> What caused you to mtr?  0% pl is pretty good. You could play quake 1.0
> through that pl and ping time. The +20ms ATL<>CHI jump in the route you'd have
> to take up with einstein/bill nye/$deity.
>
> For the 2nd trace, the 1st hop is your latency issue (plus the big jump from
> miami<>ashburn, again the limit is c.)
>
> ICMP is allowed to be dropped by intervening routers. Someone will quote an RFC
> at us shortly.
>
> Mtr without a return route is not that useful in figuring out packetloss
> because pl requires the packet make it there and back. Pl could be anywhere on
> the return route, which is probably not symmetrical. The internet stopped
> being symetrical about 20+ years ago (if it ever even loosely was), so get a friend
> to send you an mtr to your ip from the farside.
>
> (I remember a project long ago, some cgi-bin (yeah that long ago) that was
> basically a full-path forward+reverse traceroute you could hit on a selected
> server at the provider.  Rather handy. not sure if its still a thing, or what it was
> called.)
>
> /kc
>
>
> On Thu, Jul 07, 2016 at 03:17:40PM -0400, Phillip Lynn said:
>    >Hi all,
>    >
>    >  I am writing because I do not understand what is happening.  I ran mtr
>    >against our email server and www.teco.comand below are the results.  I am
>    >not a network engineer so I am at a loss.  I think what I am seeing is
>    >maybe a hand off issue, between Frontier and Level3Miami2. If I am correct
>    >then what can I do?
>    >
>    >  My system is running Centos 6.5 Linux.
>    >
>    >Thanks,
>    >
>    >Phillip
>    >
>    >
>    >
>    >(! 1011)-> sudo mtr -r netwolves.securence.com
>    >HOST: xxxxx at netwolves.comLoss%   Snt   Last   Avg Best  Wrst StDev
>    >  1. 172.24.109.1                  0.0%    10    0.6 0.6 0.6   0.7   0.0
>    >  2. lo0-100.TAMPFL-VFTTP-322.gni  0.0%    10    3.2 2.0 1.0   4.3   1.2
>    >  3. 172.99.44.214                 0.0%    10    4.0 4.9 2.3   6.9   1.5
>    >  4. ae8---0.scr02.mias.fl.fronti  0.0%    10    9.3 9.1 7.5   9.8   1.0
>    >  5. ae1---0.cbr01.mias.fl.fronti  0.0%    10    8.9   9.1   7.6 9.7 0.7
>    >  6. lag-101.ear3.Miami2.Level3.n 80.0%    10    9.0   8.9   8.8 9.0 0.1
>    >  7. 10ge9-14.core1.mia1.he.net    0.0%    10   14.3 13.0 7.6  18.1   4.3
>    >  8. 10ge1-1.core1.atl1.he.net     0.0%    10   25.6  33.2 22.4  99.7  23.6
>    >  9. 10ge10-4.core1.chi1.he.net    0.0%    10   45.6  51.8 45.5  82.7  12.5
>    > 10. 100ge14-2.core1.msp1.he.net   0.0%    10   53.6  63.9 53.6 125.2  21.8
>    > 11. t4-2-usi-cr02-mpls-usinterne  0.0%    10   53.2  73.1 53.2 225.6  54.0
>    > 12. v102.usi-cr04-mtka.usinterne  0.0%    10   53.2  53.9 53.2  55.3   0.6
>    > 13. netwolves.securence.com       0.0%    10   53.4  53.9 53.4  55.4   0.7
>    >
>    >(! 1014)-> sudo mtr -r www.teco.com
>    >HOST: xxxxx at netwolves.comLoss%   Snt   Last   Avg Best  Wrst StDev
>    >  1. 172.24.109.1                  0.0%    10    0.6 0.6 0.6   0.7   0.0
>    >  2. lo0-100.TAMPFL-VFTTP-322.gni  0.0%    10  104.8 81.4 1.1 113.2  43.2
>    >  3. 172.99.47.198                 0.0%    10  115.0 77.8 2.9 115.0  40.2
>    >  4. ae7---0.scr01.mias.fl.fronti  0.0%    10  111.1 80.2 8.5 113.5  41.3
>    >  5. ae0---0.cbr01.mias.fl.fronti  0.0%    10  105.9  82.2   7.6 115.4 33.8
>    >  6. lag-101.ear3.Miami2.Level3.n 70.0%    10  116.1  80.2   8.5 116.1 62.0
>    >  7. NTT-level3-80G.Miami.Level3.  0.0%    10  110.0 81.5 9.0 120.3  41.9
>    >  8. ae-3.r20.miamfl02.us.bb.gin.  0.0%    10  119.8  84.0 10.0 119.8  38.5
>    >  9. ae-4.r23.asbnva02.us.bb.gin. 10.0%    10  137.4 107.6 30.1 142.7  45.7
>    > 10. ae-2.r05.asbnva02.us.bb.gin.  0.0%    10  135.0 109.9 36.6 140.0  39.1
>    > 11. xe-0-9-0-8.r05.asbnva02.us.c  0.0%    10  147.5 125.6 49.4 165.5  41.1
>    > 12. 24.52.112.21                  0.0%    10  158.6 124.0 49.6 161.3  41.5
>    > 13. 24.52.112.42                  0.0%    10  151.0 127.7 52.2 159.0  41.2
>    > 14. ???                          100.0    10    0.0 0.0 0.0   0.0   0.0
>    >
>    >--
>    >Phillip Lynn
>    >Software Engineer III
>    >NetWolves
>    >Phone:813-579-3214
>    >Fax:813-882-0209
>    >Email: phillip.lynn at netwolves.com
>    >www.netwolves.com
>    >
>

None taken,

   We are having issues with our email and loading some web pages. I 
used mtr to try and find if there is a possible connection issue.  I 
just need to understand what is happening , and be able to explain the 
output showing the 80% packet loss .  We are not pointing fingers, just 
looking to understand the issue better.

Thanks

-- 
Phillip Lynn
Software Engineer III
NetWolves
Phone:813-579-3214
Fax:813-882-0209
Email: phillip.lynn at netwolves.com
www.netwolves.com




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