100 Mbps Ethernet performance problem 1

[hansvanbreen]

We experience very poor performance on our 100 Mbps ethernet. Research showed that there is a configuration mismatch between the Cisco switch and the Ethernet adapter in the RS6000. The solution is to configure both devices to autonegotiate speed and full or half duplex operation.
Reverting the switch to autonegotiate was easy but the RS6000 won't let me change the adapter propereties:
I first brought the interface down:

Change / Show a Standard Ethernet Interface

Type or select values in entry fields.
Press Enter AFTER making all desired changes.
[Entry Fields]
Network Interface Name en0
INTERNET ADDRESS (dotted decimal) [10.131.1.22]
Network MASK (hexadecimal or dotted decimal) [255.255.0.0]
Current STATE down +
Use Address Resolution Protocol (ARP)? yes +
BROADCAST ADDRESS (dotted decimal) []

Then I tried to change the adapter parameters:

Change / Show Characteristics of an Ethernet Adapter

Type or select values in entry fields.
Press Enter AFTER making all desired changes.

[Entry Fields]
Ethernet Adapter ent0
Description IBM 10/100 Mbps Ethernet PCI Adapter (23100020)
Status Available
Location 10-80
TRANSMIT queue size [256] +#
HARDWARE RECEIVE queue size [256] +#
RECEIVE buffer pool size [384] +#
Media Speed Auto_Negotiation +
Inter-Packet Gap [96] +#
Enable ALTERNATE ETHERNET address no +
ALTERNATE ETHERNET address [0x000000000000] +
Enable Link Polling no +
Time interval for Link Polling [500] +#
Apply change to DATABASE only no +

Method error (/usr/lib/methods/chgent):
0514-062 Cannot perform the requested function because the specified device is busy.

The question is what keeps the device busy? What else has to be stopped in order to be able to change the adapter parameters?

Hans

 

[PSD]

Hans,

You have to detach it as well in order to make a speed change on the fly. i.e.

ifconfig en0 detach

I would say however that using auto-neg is never a good idea because 9/10 the adapter will drop to 10 half or 10 full so you drop from a theoretical maximum of 12 megs a second to about 1.5 megs a second. I have used all types of switches and all you need to do on the Cisco switch is force the adapter port to 100 full duplex, by default it is normally 100 half duplex. In that instance the adapter will suffer from poor performance. Just set both to 100-full.

Cheers

PSD
IBM Certified Specialist - AIX V4.3 Systems Support
IBM Certified Specialist - AIX V4 HACMP

 

[hansvanbreen]

PSD, thanks for the solution. I was now able to change the setting and test the current speed:

ftp> get /usr/ftp10mb.Z
200 PORT command successful.
150 Opening data connection for /usr/ftp10mb.Z (10599033 bytes).
226 Transfer complete.
10644249 bytes received in 1.146 seconds (9070 Kbytes/s)
local: /usr/ftp10mb.Z remote: /usr/ftp10mb.Z
ftp>
ftp> put /usr/ftp10mb.Z
200 PORT command successful.
150 Opening data connection for /usr/ftp10mb.Z.
226 Transfer complete.
10644249 bytes sent in 1.054 seconds (9863 Kbytes/s)
local: /usr/ftp10mb.Z remote: /usr/ftp10mb.Z
ftp>

Thanks again,
Hans

 

[PSD]

Hans,

You are getting about 10 megs a second at the moment, but keep an eye on it if you have set auto_neg because it can drop to 10.

Cheers

Paul PSD
IBM Certified Specialist - AIX V4.3 Systems Support
IBM Certified Specialist - AIX V4 HACMP

 

[mrn]

The guys above have already answered this question really, but I had the same problem. Hard setting each end to 100 Full sorted the problem.

--
| Mike Nixon
| Unix Admin
|

http://www.instantflashshop.com

----------------------------

 

[Yegolev]

Echo... we have never, ever been able to make auto-neg work. Set to 100-full (like our switches) works. Still "testing" 1GB enet.