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What may slow down the network speed in LAN of cluster ?
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hwchen
n00b
n00b


Joined: 22 Aug 2003
Posts: 10
Location: Taiwan

PostPosted: Fri Aug 29, 2003 10:06 am    Post subject: What may slow down the network speed in LAN of cluster ? Reply with quote

Hi, everyone:

I am preparing to build a cluster for parallel calculation. But I have a serious problem now.
Today I used a package named netperf to test the speed inner the Local Area Network. I have 3 machines at first: master(192.168.2.254), hydrogen(192.168.2.1), helium (192.168.2.2),and the OS on them are all gentoo 1.4. The speed of the transparency are all about 50~100 Mbit/sec. I have disabled the firewall (iptables) on master already. The net-card are all Intell e1000 in the 64-bit PCI slot of ASUS A7M266D.and a gigabit switch is used. The line connected to the gigabit switch are all CAT 6 for gigabit transparency. It made me feel so strange so I used another machine build with Redhat (named lithium).

hydrogen <--> helium 50~100 Mbit /sec
hydrogen --> lithium 50~100 Mbit/sec
lithium -->hydrogen 100~200 Mbit/sec

I have tested other machines all built with RedHat and the flow is about 300~600 Mbit/sec.

Is there any security reason lead my low flow of networks? I used the USE flag "tcpd" in /etc/make.conf, is that the reason? The service I used on the machine are only metalog, vcron and sshd. Should I change some default configuraion of the system?

Please do help me :cry:
I am really in troble and do not know what to do
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think4urs11
Bodhisattva
Bodhisattva


Joined: 25 Jun 2003
Posts: 6659
Location: above the cloud

PostPosted: Fri Aug 29, 2003 9:00 pm    Post subject: Reply with quote

Hi!

First step (if not done already of course) should be to use fixed settings.

If you want 1GB then get sure your NIC/Switch do exactly this and no 'auto-magic'.

Therefore configure static settings for speed and duplex on all NIC - mii-tool does the job.
And configure the switch ports accordingly. Consult the doku for this
If it's a Cisco:
- configure terminal
- interface giga0/port-number
- speed 1000
- duplex full
- exit
- exit
- copy running start
- quit

Having one one end of a connection on fixed settings and the other on 'auto' can give you VERY strange results in throughput testing...

HTH
T.
_________________
Nothing is secure / Security is always a trade-off with usability / Do not assume anything / Trust no-one, nothing / Paranoia is your friend / Think for yourself
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hwchen
n00b
n00b


Joined: 22 Aug 2003
Posts: 10
Location: Taiwan

PostPosted: Sun Aug 31, 2003 3:27 pm    Post subject: Reply with quote

Thanks to Think4UrS11 :lol:

I have run mii-tool for the status of my e1000 card and found the only 10Mbit of trasparency had been autonegociated.

The other thing I learned is that the mii-tool is only for 100base as the fastest as support. I have anothoer tool called ethtool is also collected in the emerge tree and it is more userfull to use. If anyone has the same problem, use the tool first .

I am not on the local machine now, I will try the trasparency flow tomorrow!!

Thanks Think4UrS11 again :D
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