[bdNOG] Fwd: Problem accessing www.bb.org.bd.

Brian Candler brian at nsrc.org
Mon Sep 14 13:49:46 BDT 2015


On 14/09/2015 07:52, Fakrul Alam wrote:
> www.bb.org.bd <http://www.bb.org.bd> site are seriously overloaded...
>
That is one theory. However, people say that if they connect via Qubee 
they get fast response.

Another theory is that there is substantial packet loss over certain 
paths, causing TCP delays / retransmissions. You may be able to infer 
this by taking a packet capture:

tcpdump -i eth0 -w bb.pcap -nn

and then analysing bb.pcap looking for retransmissions, e.g. by hand, or 
by using tcptrace and xplot.
http://www.tcptrace.org/tcptrace-manual/manual/node12_ct.html

If it's a load problem (either server load or network load) I would 
expect the issue to vary by time of day, and be noticeably better in the 
middle of the night.

By the way: this is a *bank*, and this is 2015. Do you really still need 
to force SSLv3 to connect to them, rather than TLS? That is totally 
broken. It won't be long before web browsers disable SSLv3, because of 
its known security problems.

> $ curl -o /dev/null -s -w 
> %{time_connect}:%{time_starttransfer}:%{time_total}\\n --sslv3 
> https://www.bb.org.bd:443
> 0.072:120.083:704.965
That is an excellent start. It would be really helpful if people could 
make measurements like this from different points and at different times 
of day, and for someone to collate the results. This will help to 
demonstrate that there *is* really a problem, and help to pinpoint what 
it is.

For comparison, here's what I get from a VM in the UK (at 
bytemark.co.uk): three successive tests made on 2015-09-14 at 07:40 UTC

3.912:0.000:3.912
1.001:0.000:1.001
0.448:0.000:0.447

Given the latency from UK to Bangladesh I'd say this is understandable, 
although if everything is working well I would expect the third result 
to be consistently achieved, not the first result.

Regards,

Brian.

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