[84123] in North American Network Operators' Group
RE: level3.net in Chicago - high packet loss?!?
daemon@ATHENA.MIT.EDU (Min Qiu)
Tue Sep 6 10:50:20 2005
Date: Tue, 6 Sep 2005 10:49:55 -0400
From: "Min Qiu" <mqiu@pop2pop.com>
To: "Network Fortius" <netfortius@gmail.com>, <nanog@merit.edu>
Errors-To: owner-nanog@merit.edu
Stef,
> -----Original Message-----
> From: Network Fortius [mailto:netfortius@gmail.com]=20
> Sent: Tuesday, September 06, 2005 10:25 AM
> To: nanog@merit.edu
> Subject: Re: level3.net in Chicago - high packet loss?!?
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> And how exactly would you interpret the number returned by net_loss =20
> (int), in a column called "LOSS", in reference to reachability of a =20
> "hop" between two end points:
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> int net_loss(int at)
> {
> if ((host[at].xmit - host[at].transit) =3D=3D 0)
> return 0;
> /* times extra 1000 */
> return 1000*(100 - (100.0 * host[at].returned / (host[at].xmit - =20
> host[at].transit)) );
> } ?
This piece of code is modified by me (all mistake is mine). It=20
converts the the drop to percentage. x 1000 was a trick to handle
none int returned by the function. This was an issue I did not=20
have a clear answer.
Regarding to you original post. Your trace end2end (last hop) has=20
0.0% drop proved the entire path was free of packet loss. The drop=20
in the middle of the path could be related to ICMP rate limit or=20
other things. Should it was a congestion in the X hop, every hop=20
after X would be impacted by it. Thus X+1, X=3D2... has to be > 0.0%.
Hope this help,
Min
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> Thanks,
> Stef
> Network Fortius, LLC
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> On Sep 6, 2005, at 7:45 AM, Robert E.Seastrom wrote:
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> >
> > Network Fortius <netfortius@gmail.com> writes:
> >
> >
> >> Anybody having any idea why such a high packet loss on lever3's
> >> network, in Chicago?
> >>
> >
> > End-user misinterpreting output from MTR. This network does not
> > appear to have any packet loss end-to-end.
> >
> > ---Rob
> >
> >
> >
> >> Stef:~ scm$ mtr -r www.yahoo.com
> >> ...
> >> tbr1-p010802.cgcil.ip.att.net 0% 16 16 15.12
> >> 24.21 49.26
> >> ggr2-p310.cgcil.ip.att.net 0% 16 16 13.18
> >> 42.66 118.99
> >> so-1-1-0.edge1.chicago1.level3.net 0% 16 16 14.48
> >> 35.84 126.48
> >> so-2-1-0.bbr1.chicago1.level3.net 63% 6 16 14.44
> >> 43.74 79.97
> >> =20
> =20
> >> ^^^^^^^
> >> as-1-0.bbr2.sanjose1.level3.net 0% 16 16 61.95
> >> 80.64 176.01
> >> ge-10-2.ipcolo3.sanjose1.level3.net 0% 16 16 63.37
> >> 95.61 148.46
> >> unknown.level3.net 0% 16 16 63.34
> >> 86.46 168.62
> >> unknown-66-218-82-217.yahoo.com 0% 16 16 62.09
> >> 88.91 127.58
> >> p4.www.scd.yahoo.com 0% 16 16 64.51
> >> 89.96 183.79
> >>
> >> TIA,
> >> Stef
> >> Network Fortius, LLC
> >
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