Adapter speed Question

[monman]

After connecting a fibre Gig Ethernet o a p660 I can only achieve the equiv of a 100 card through ftp tests. Card is set to Auto and the switch is set to 1000. Any ideas ?

Also, does anyone know the command for displaying card speeds.

Thanks
mon

 

[PSD]

Monman,

Well using auto negotiate is the problem set your media_speed to the max. shown in the F4 list.

In terms of finding out how fast your card is running you can`t really with any certainty, you can try

enstat -d <adapter>

Towards the bottom somthing similar will be shown, check out media speed running (this can be accurate).

IBM 10/100 Mbps Ethernet PCI Adapter Specific Statistics:
------------------------------------------------
Chip Version: 26
RJ45 Port Link Status : down
Media Speed Selected: 10 Mbps Half Duplex
Media Speed Running: Unknown
Receive Pool Buffer Size: 384
Free Receive Pool Buffers: 128
No Receive Pool Buffer Errors: 0
Inter Packet Gap: 96
Adapter Restarts due to IOCTL commands: 1
Packets with Transmit collisions:
1 collisions: 2339668 6 collisions: 39256 11 collisions: 2206
2 collisions: 1326546 7 collisions: 17944 12 collisions: 2020
3 collisions: 687356 8 collisions: 9348 13 collisions: 1801
4 collisions: 284956 9 collisions: 4940 14 collisions: 1653
5 collisions: 98589 10 collisions: 2653 15 collisions: 1443
Excessive deferral errors: 0x0
PSD
IBM Certified Specialist - AIX V4.3 Systems Support
IBM Certified Specialist - AIX V4 HACMP

 

[monman]

The max shown is 100. Does this mean that I should set my Gigabit card to 100mbs ?

Mon

 

[PSD]

Monman,

No it should be auto neg. thinking about this, the other options are only valid for a 10/100.

Make sure that the JUMBO frames option is set to yes, and make sure your switch can support JUMBO Frames.

You must also down the interface and set the MTU size to 9000+ setting jumbo frames ALONE will not enable the larger packet size.


some &quot;no&quot; options off the tip of my head:

no -a check for:
rfc1323 = 1 THIS IS IMPORTANT


tcp_recvspace = 131072
tcp_sendspace = 131072 Match these on the send and
recieve hosts


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

 

[monman]

PSD,

I've checked for the values you stated above and have the following on this box :

rfc1323 = 0
tcp_recvspace=16384
tcp_sendspace=16384


What do these values represent and What impact will it have if I change them ?

Also you refer to changing the MTU size ? Is this Software Transmit queue size ??

Thanks fo your help,
Mon

 

[Yegolev]

We have so far been unsuccessful in getting gigabit to run in our environment. We are working with IBM on this. Not my project (as usual) so I am not up-to-date on the details.

 

[monman]

PSD,

Do you have any update on my previous note ?

cheers,
Mon

 

[PSD]

monman,

No I am refering to the maximum IP packet size for the adapter, as shown via:

lsattr -El en0

mtu = 1500

On gigabit ethernet it should be set to 9000 or greater along with jumbo frames set to TRUE. Post up:

lsattr -El ent0

lsattr -El en0

In terms of tuning :

tcp_send and receive space are the default sizes of the TCP socket send and receive buffer, and rfc1323 must be set to 1 in order for the TCP values to exceed 64KB, and my suggestions are 131072 so it needs to be set to 1.

In terms of risk it certainly should not make things worse that is for sure, but it may be worth doing it in a maintenance window :

just do:

no -o rfc1323=1
no -o tcp_sendspace=131072
no -o tcp_recvspace=131072

Also, repeat this on the target system. Test an ftp or whatever.

Then you can just re-set the values back or reboot the system to get back to the defaults.

Does that clear things up a little?

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