You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 14 Next »

Looking at the average round trip times between monitor.niit.edu.pk and pinger.uettaxila.edu.pk there is a sudden step down drop on April 25th 2011 from ~30ms to ~ 5ms.  The reverse step happens on May 7th 2011.  There is also an outage between March 17th and April 15th. 

This is seen in both the  SLAC and SEECS archive sites at http://www-wanmon.slac.stanford.edu/cgi-wrap/pingtable.pl?file=average_rtt&by=by-node&size=100&tick=last60days&from=PK.NIIT.EDU.N2&to=Pakistan&ex=none&only=all&dataset=hep&percentage=any and http://pinger.seecs.edu.pk/cgi-bin/pingtable.pl?file=average_rtt&by=by-node&size=100&tick=last60days&year=2011&month=05&from=PK.NIIT.EDU.N2&to=PK.UETTAXILA.EDU.N1&ex=none&dataset=hep&percentage=any

Looking at the raw data read from NIIT for UETAXILA it confirms RTT os ~ 5ms.

58cottrell@pinger:~>grep monitor /tmp/average_rtt-100-by-node-2011-05-01.txt \| grep uettax
monitor.niit.edu.pk pinger.uettaxila.edu.pk 3.590 4.021 4.021 4.226 5.036 6.491 7.223 6.147 6.389 7.042 7.042 5.601 5.601 6.365 6.365 6.588 4.592 4.951 5.030 7.237 6.474 5.321 4.780 4.739 monitor.niit.edu.pk pinger.uettaxila.edu.pk
pinger.uettaxila.edu.pk monitor.niit.edu.pk . 4.438 4.438 5.706 5.235 6.316 6.521 7.613 5.898 6.036 6.036 6.088 6.088 5.835 5.835 6.321 6.665 6.665 6.280 7.356 9.075 5.183 4.605 4.654 pinger.uettaxila.edu.pk monitor.niit.edu.pk

The drop in RTT is also confirmed looking at the FNAL graph:

Looking at the traceroutes from monitor.niit.edu.pk to uettaxila on one of the days of low Avg_RTT (here 5/1/2011) one gets the following message:

traceroute server busy at the moment. Please try again later. See The Naming System for information on host.domain and Addresses for information on Internet addresses.

To get a better view of the situation, we try to look at the reverse route i.e from pinger.uettaxila.edu.pk to monitor.niit.edu.pk. The smokeping graph thus obtained is:

The smokeping graph shows that the node was showing a fluctuating UP/DOWN behavior during the last three months. However, the drop in Avg_RTT is observed here also (see at 2011-05-02).

Looking at the traceroutes from pinger.uettaxila.edu.pk to monitor.niit.edu.pk on one of the days of low Avg_RTT (here 5/1/2011) following output is observed:

Executing exec(traceroute, -m 30 -q 3 -f 3, 115.186.131.81, 140)
traceroute to 115.186.131.81 (115.186.131.81), 30 hops max, 140 byte packets
 3  rwp44.pie.net.pk (221.120.253.121)  5.457 ms  5.444 ms  5.435 ms
 4  rwp44.pie.net.pk (221.120.254.62)  6.247 ms  7.673 ms  7.667 ms
 5  rwp44.pie.net.pk (221.120.253.10)  4.555 ms  4.556 ms  4.547 ms
 6  rwp44.pie.net.pk (221.120.237.102)  4.538 ms  4.534 ms  4.529 ms
 7  58-65-175-206.nayatel.pk (58.65.175.206)  4.506 ms  4.500 ms  4.726 ms
 8  * 115-186-128-178.nayatel.pk (115.186.128.178)  6.589 ms  6.587 ms
 9  115-186-131-81.nayatel.pk (115.186.131.81)  6.429 ms  4.927 ms  4.914 ms

However today (5-13-2011) the traceroute output is given as:

Executing exec(traceroute, -m 30 -q 3 -f 3, 115.186.131.81, 140)
traceroute to 115.186.131.81 (115.186.131.81), 30 hops max, 140 byte packets
 3  rwp44.pie.net.pk (221.120.253.121)  4.624 ms  4.601 ms  4.590 ms
 4  rwp44.pie.net.pk (221.120.254.62)  4.566 ms  4.570 ms  5.414 ms
 5  rwp44.pie.net.pk (221.120.253.10)  4.267 ms  4.270 ms  4.273 ms
 6  rwp44.pie.net.pk (221.120.237.102)  4.265 ms  4.258 ms  4.773 ms
 7  58-65-175-206.nayatel.pk (58.65.175.206)  26.374 ms  26.374 ms  26.367 ms
 8  * * *
 9  * * *
10  * * *
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * 115-186-131-81.nayatel.pk (115.186.131.81)  25.631 ms  25.617 ms

This time hop 7 is taking much longer time than the last results.

Looking at the pingtable.pl data , following are the metric measurements from all the nodes in Pakistan who are monitoring uettaxila.


Jan 18th to March 2nd

March 3rd to May 15

Average RTT (ms)

63.01

29.68

Ping Unreachability (%age)

88.66

74.51

Packet Loss (%age)

7.57

3.58

TCP Throughput (bps)

1.82E+03

9.32E+03

IPDV (ms)

61.26

18.83

MOS

3.62

4.10

This is a significant improvement in terms of average RTT, packet loss, throughput and IPDV . However improvement in Ping Unreachability is lesser than expected.

PERN PoP Islamabad  to UETTAXILA

Considering that monitor.niit.edu.pk is not a pern node, we tried to analyze the performance of UET Taxila from Pern PoP Islamabad node.

looking at pingtable.pl, following trends were observed.
this can also be shown in numeric figures by looking at the following table obtained by averaging the pingtable.pl values. The Average RTT reduced by a factor of 1.91, packet loss by a factor of 3, throughput increased 3.14 times and IPDV reduced by a factor of 38.

Metrics

1st Feb-2nd Mar

3rd Mar-27th Mar

Average RTT (ms)

84.62

44.38

Packet Loss (%age)

3.68

1.23

TCP Throughput (Mbps)

1.4

4.4

IPDV (ms)

23.94

0.63

Suggestions from improvement:

Increased Link Capacity:

Reduced average RTT is a consequence of increased link capacity.

Unresolved Issues:

  • From March 17th to April 15th there is no data collected from monitor.niit.edu.pk to pinger.uettaxila.edu.pk. Was there some holiday at UET Taxila that resulted in network shutdown?
  • Dr. Anjum we carried out all the analysis on seecs (monitor.niit.edu.pk) to UETTAXILA (pinger.uettaxila.edu.pk) link. We all know that SEECS node is not on PERN. In that case is this analysis going to be acceptable to HEC? We haven't chose anyother node to analyze uettaxila because we do not have traceroutes from nodes other than SEECS. Also SEECS nodes are the most reliable nodes as Dr. Les says. (This reliability appears in smokeping graphs having lesser outages from SEECS than from other nodes.)
  • From 25th April to 7th May, the Avg_RTT was lowered from 30ms to 5ms and resumed afterwards. I along with Dr. Les tried to figure out the reason but we still are unable to find one. Sir Anjum, Can you suggest any important clue that can lead us to the reason why Avg_RTT was lowered so much?
  • Since Friday I am unable to load SEECS pingtable and the smokeping graphs from SEECS pingtable. I need them for analysis. Can someone get this resolved so that I can make report as soon as possible.
  • No labels