Speed, Duplex, and Flow Control

[bevans]

Hello all. I am going a bit crazy over here trying to work out some network issues with Dell. I have a few Dell PowerEdge servers connected to a:

10/100/1000BaseT Ethernet WS-X6148-GE-TX

All servers are running 1.0GB NICs. Some say that I should use auto port settings. Other say manual settings for speed, duplex, and flow control as well as the servers NIC.

Does anyone have any thoughts or experience with this? Thanks.

- Bill

[Edison Ortiz]

That's a religious battle :) I personally go for auto/auto all around.

Check out this article:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00800a7af0.shtml

[Jon Marshall]

Bill

I have often hard-coded 10/100 interfaces because of auto-negotiation problems but in my experience i have found gigabit auto-negotiation to be very reliable.

Jon

[d-mark]

Hi,

I've no experience with exactly this hardware constellation.

But when it comes to ethernet speed and duplex settings, the one thing I can say is use the same setting on both sides, regardless if it is auto or a fixed setting. But check if the connections woks fine by looking at the (error) counters on both interfaces if possible.

HTH

Mark

[Danilo Dy]

Hi Bill,

Are you having problem with auto/auto setting?

If you think and monitored that the system will not utilize more than 100Mbps, I suggest hardcoding them to 100Mbps/Full-duplex (switch and server). Hardcoded 100Mbps/Full-duplex is faster than 1000Mbps/Half-duplex if utilization is less than 100Mbps.

Take note that hardcoding 1000Mbps/Full-duplex in the switch have a downside since most server OS only support hardcoding the speed to GE (1000Mbps) but not the duplex (only auto).

If bandwidth utilization will exceed 100Mbps, auto/auto is recommended - make sure you have a good quality cable Cat 5e or Cat 6 and monitor the switch port for errors and duplex/speed mismatch.

Regards,

Dandy

[shiva_ial]

bill,

the card what u mentioned has capability of suiting itself to the speed other end prefers on negotiation

which means in simple

either 10mbps,or 100 mbps or 1000 mbps depends

on other end speed

if you are very sure on other end speed use

manual settings else use auto.

rgds

shiva

[bevans]

Thank you all for your posts. I appreciate it. I will look further in to what you have detailed.

[bevans]

Hello all again. I took a look further at my configs. All servers are set to auto in the NIC software. The switch is set to AUTO for duplex and 1000 manually for speed. I can change the speed back to AUTO. However, the ports/interfaces have 0 error messages in 2-3 months.

Any other ideas?

- Bill

[Edison Ortiz · Accepted solution]

You should match the settings, if the servers are running Auto/Auto, the switchport should have auto/auto as well.

Errors may not be present in the counters but you may experience speed degradation.