Oh and to verify some things i used iperf and send big batch of udp
traffic at 500mbit/s and it made it with 0.004% packet loss so the
bandwidth through to the
external link isn't the problem either..
Arie Vayner (avayner) wrote:
Paul,
Let's see if I get it strait.
If you run the server at 1G, and test locally on the same switch, you
get 100MB/s?
If you run the server at 1G, and test from the WAN (beyond the Level 3
connection) you get 1.3MB/s?
If you run the server at 100M, and test from the WAN (beyond the Level 3
connection) you get 11.5MB/s?
If you run the same test from the local 6500 (not the same switch where
the server is on, but the one used to connect to Level3) with 1G/100M?
If the port on the upstream to Level 3 is limited to a higher rate
(let's say 300M), you would be able to pass on average the full 100Mbps
rate (hence 11.5MB/s) but if you run the server at 1G, it would result
in the server being able to overload the link with bursts at 1G rate,
while the link is only (let's say) 300Mbps. This would cause Level3 to
drop packets, which would dramatically affect the TCP window state of
the download session.
This situation can be fixed by removing the rate limit or by using
egress shaping (which is not supported natively on the 6500 so it's not
easy to test).
Can you please answer the above points so we can see if we are on the
same page?
Tnx
Arie
-----Original Message-----
From: Paul [mailto:[email protected]]
Sent: Sunday, June 27, 2010 11:32
To: Arie Vayner (avayner)
Cc: [email protected]
Subject: Re: [c-nsp] Centos upload speed slower on 1000m than 100m over
WAN links
No, and like i said, i get 11.5MB/s transfer rate if i set my local port
to 100mbits, and i get 1.3MB/s if i set it to 1000mbps
yet internally on the same switch i get 100MB/s between servers
gigabit..
If the port was limited in any way i wouldn't get 11.5MB/s transfer rate
by setting my local port to 100mbits.
Arie Vayner (avayner) wrote:
Paul,
What kind of a link are you getting from Level3?
Could it be a subrate link (i.e. a GigE port with some lower bandwidth
service?)
Arie
-----Original Message-----
From: Paul [mailto:[email protected]]
Sent: Sunday, June 27, 2010 11:10
To: Arie Vayner (avayner)
Cc: [email protected]
Subject: Re: [c-nsp] Centos upload speed slower on 1000m than 100m
over
WAN links
Even plugged directly into edge router (cisco 6500) connected to
level3
and tested on another server on level3 5 hops away.
When the port is set at 100 i can get full 100m speed, when i set it
at
1g I get less, which makes absolutely no sense and I'm totally
stumped.
Arie Vayner (avayner) wrote:
Paul,
I am not really aware of the fine details on the CentOS thingie, but
can
you describe how the upstream network connection of that server looks
like? What lies beyond the NIC in the next few network hops.
Thanks
Arie
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Paul
Sent: Sunday, June 27, 2010 09:04
To: [email protected]
Subject: [c-nsp] Centos upload speed slower on 1000m than 100m over
WAN
links
I'm not even sure this is the right forum but since we use mainly
Cisco
equipment I'll give this a shot. :)
I have tried several centos based servers and compiled various
kernels
and the results have been extremely weird.
90% of the cases the remote hosts can download from a server at
1-5megabytes per second, and most of these are over
the internet ranging from 30-200ms away. Local (1ms or less) is
super
fast 100MB/s for example.
Ok that sounds normal since it's going over the internet, etc. But
here's the )(!...@*! part..
If I set the port speed to 100 megabits full duplex on the switch and
server , the clients that get 1-5MB/s now get 11MB/s which is
approximately the limit of the 100mbit port.
Totally stumped here, tried different nics, servers, even 4 different
switches. Is a very interesting problem and I'm probing to see
if anyone else has encountered it.
So far the only OS i have tried is centos, but different versions and
kernels and hardware.
All the switches/routers are Cisco based, but I seriously doubt that
has
anything to do with this. :P
--
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Phone: 1-514-907-0050 x 215
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