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20030825: LDM latency on Rossby



>From: Mike Voss <address@hidden>
>Organization: SJSI
>Keywords: 200308251458.h7PEwJLd022746 IDD packet shaping

Hi Mike,

>Well, it's that time of year, I'm getting latencies in my data flow and
>I'm trying to figure out where the bottle neck is.  Posted below is a
>traceroute, could someone inform me from their experience whether those
>latencies are bad enough (after hop 10) to cause latency in my data?

Looking at the combination of the small traceroute times and the
pattern of latencies seen in your IDS|DDPLUS feed:

http://www.unidata.ucar.edu/cgi-bin/rtstats/iddstats_nc?IDS|DDPLUS+rossby.met.sjsu.edu

my gut reaction is that SJSU has turned on some sort of packet shaping
software that does not allow port 388 data to pass unrestricted.
I recommend that you contact your network group and ask them when
they turned on the packet shaping (jump right to the heart of the matter
instead of asking them if they turned on packet shaping), and open
a discussion of them allowing port 388 traffic to flow with no
restriction.

>And there are two *'s, which indicate a timeout on the transmission of
>a packet if I understand correctly, is this cause for concern, and how
>can I troubleshoot this now that ping has largely been disabled over
>the Internet.

I am 99% sure that the problem originates in your network.

>And a related question: How many of these sites
>http://www.unidata.ucar.edu/staff/chiz/rtstats/siteindex.shtml (in
>rough terms) are using Internet2?

I don't know right off, but there are quite a few Unidata sites that
do have I2 connectivity.

>My university has informed me that we
>have the ability to get on I2 for 25K a year, so I'm looking for
>partners. I'm sure this would greatly increase our ability to receive
>and feed data. Thanks for your help,

If your problem was one of overall bandwidth, then getting an I2
connection would be worthwhile.  We were working under the impression
that the existing network connection into SJSU was good (big pipe).
If this is not the case, then you may be seeing inteference from
returning students using existing resources.  In this case, getting
an I2 connection that is isolated from the other traffic would be
very useful.  Whether or not it is worth $25K to you is, of course,
up to you/your program.

By the way, as a simple test I would see if things like FTP and
web access during the hours of peak IDD latency is slow.  If they
are for a variety of activities (e.g., small and large FTP transfers),
then you may be looking at SJSU network congestion; if they are not,
I would pursue the investigation of packet shaping by your network
group.

>-Mike
>
>
>traceroute to thelma.ucar.edu (192.52.106.21), 30 hops max, 40 byte packets
> 1  gateway-97.met.sjsu.edu (130.65.97.254)  7.589 ms  21.505 ms  5.209 ms
> 2  backbone1.science.sjsu.edu (130.65.80.1)  2.302 ms *  2.905 ms
> 3  cc1omnicore.sjsu.edu (130.65.5.254)  2.046 ms  1.818 ms  1.793 ms
> 4  horst.sjsu.edu (130.65.11.1)  2.193 ms  2.119 ms  2.098 ms
> 5  cisco7204.sjsu.edu (130.65.11.5)  2.317 ms  2.415 ms  2.354 ms
> 6  QSV-SJSU-ATM.CSU.net (137.145.203.105)  13.455 ms  11.947 ms  11.678 ms
> 7  QSV-GSR--QSV-7513.CSU.net (137.145.202.221)  4.714 ms  5.389 ms  3.746 ms
> 8  QSV-GSR-C2.GE.calren2.net (137.164.12.165)  3.829 ms  3.592 ms  3.693 ms
> 9  Abilene--QSV.POS.calren2.net (198.32.249.162)  14.528 ms  13.957 ms  14.12
> 5 ms
>10  dnvrng-snvang.abilene.ucaid.edu (198.32.8.2)  38.496 ms  38.739 ms  40.044
>  ms
>11  * 192.43.217.129 (192.43.217.129)  39.155 ms  40.804 ms
>12  gin.ucar.edu (128.116.254.240)  46.929 ms  40.202 ms  44.934 ms
>13  128.117.243.75 (128.117.243.75)  40.084 ms  39.601 ms  39.776 ms
>14  thelma.ucar.edu (192.52.106.21)  39.767 ms  39.903 ms  40.216 ms

Cheers,

Tom

>From address@hidden Mon Aug 25 09:52:50 2003

Tom,

Just an FYI-

Because I'm having latency issues, I separated out the IDS|DDPLUS feed
from the HDS so I don't get my text data hung up when the HDS data is
latent, which it is now constantly for some reason. I sent in a
separate request for assistance on the latency issue.

Cheers,

-Mike