Low BW between Mountain View and OR -- why?

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1

Hi,

I have a server in Mountain View and i am doing a speedtest with a server
in Oregon. I see that the upload/download BW that i am getting is low --
around 10.0Mbps and 5.0Mbps.

gkent@ubuntu:~/ics$ speedtest-cli --server 4082
Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Comcast Cable (50.250.251.210)...
Hosted by Eastern Oregon Net, Inc. (La Grande, OR) [913.33 km]: 120.959 ms
Testing download speed........................................
Download: 5.08 Mbits/s
Testing upload speed..................................................
Upload: 10.89 Mbits/s

When i check my connectivity with a server in NYC, its much better, though
the server is much further away.

gkent@ubuntu:~/ics$ speedtest-cli --server 2947
Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Comcast Cable (50.250.251.210)...
Hosted by Atlantic Metro (New York City, NY) [4129.02 km]: 307.568 ms
Testing download speed........................................
Download: 38.52 Mbits/s
Testing upload speed..................................................
Upload: 10.62 Mbits/s

I am trying to understand why this is so? I would wager that NYC being
further away would give me a worse throughput than OR, but the speedtest
tells me otherwise.

The 2nd and more puzzling observation is that while OR is giving a download
of around 5.08Mbps, it will improve and become much better later in the
day. There are times when i see it going up as high as 48Mbps.

Sometimes while a transfer is in progress i see that my download suddenly
goes down from 48Mbps to 2Mbps.

Can somebody here tell me why such a drastic fluctuation is seen?

Thanks, Glen

2

Try a traceroute to the site in Orefon and see where the bottle neck is?
Could also be that the speedtest server in OR is bogged down...

-Mike

3

Tue, Feb 17, 2015 at 11:47:04AM +0530, Glen Kent wrote:

I have a server in Mountain View and i am doing a speedtest with a
server in Oregon. I see that the upload/download BW that i am
getting is low -- around 10.0Mbps and 5.0Mbps.

gkent@ubuntu:~/ics$ speedtest-cli --server 4082
Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Comcast Cable (50.250.251.210)...
Hosted by Eastern Oregon Net, Inc. (La Grande, OR) [913.33 km]: 120.959 ms
Testing download speed........................................
Download: 5.08 Mbits/s
Testing upload speed..................................................
Upload: 10.89 Mbits/s

When i check my connectivity with a server in NYC, its much better, though
the server is much further away.

gkent@ubuntu:~/ics$ speedtest-cli --server 2947
Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Comcast Cable (50.250.251.210)...
Hosted by Atlantic Metro (New York City, NY) [4129.02 km]: 307.568 ms
Testing download speed........................................
Download: 38.52 Mbits/s
Testing upload speed..................................................
Upload: 10.62 Mbits/s

I am trying to understand why this is so? I would wager that NYC being
further away would give me a worse throughput than OR, but the speedtest
tells me otherwise.

Packet loss or just congestion on the path (resulting in packet loss
again) that makes your TCP windows to shrink and not letting you to
get close to either your allocated BW on the channel to OR or your
maximal throughput per TCP stream that is governed by the maximal size
of the TCP buffer? There could be some shaping as well, but this
might be not your case, since it fluctuates. However, many interesting
things could happen.

iperf in UDP mode should give you fairly good overview of what't
happening with bandwidth and packet loss. And iperf in TCP mode with
varying number of streams (and obtained scaling of throughput or lack
of it) should give you some hints on what's possibly going on.

I also assume that you're talking about TCP and your bandwidth-delay
product is used to tune TCP buffer sizes. If not, I'd recommend
checking
  TCP Tune | PSC

The 2nd and more puzzling observation is that while OR is giving a
download of around 5.08Mbps, it will improve and become much better
later in the day. There are times when i see it going up as high as
48Mbps.

Sometimes while a transfer is in progress i see that my download
suddenly goes down from 48Mbps to 2Mbps.

Varying routing during the day, fluctuating congestion and many other
things could happen. Probably here something like smokeping will give
you an overview of the RTT (if it varies) and loss on the ICMP. ICMP
loss isn't neccessarily coupled to UDP/TCP due to the QoS and other
stuff that can happen on WAN, so it will provide just additional hints,
not the complete answer.

Can somebody here tell me why such a drastic fluctuation is seen?

No answers here, sorry, just some hints and possibilities.

4

You are probably testing with different sites in Oregon.
La Grande is different than Portland/Salem/Corvallis, etc.
I would expect traffic to eastern Oregon to be slow.

/jgk