Troubleshooting
Problem
4-port gigabit Ethernet Switch Module (ESM)requires Blade Flow Control activation. Without Blade Flow Control, traffic on a 1 Gigabit link between a Blade and the ESM may cause the connection to experience data loss.
Resolving The Problem
| Source |
|---|
RETAIN tip: H182901
| Symptom |
|---|
With high bandwidth, peak volume, and burst traffic on a 1 Gigabit link between a Blade and the Ethernet Switch Module (ESM), the connection may experience data loss and require retransmissions.
The ESM Port Setting status indicates that the Link Flow Control is Enabled on the blade connection, and the ESM is ready to participate in Flow Control. However, due to the low level hardware implementation of the ESM/Blade connection on the ESM, Flow Control will not be Enabled if the Blade Flow Control setting is Auto.
| Affected configurations |
|---|
The system may be any of the following IBM eServer servers:
- BladeCenter, type 8677, any model
- BladeCenter HS40, type 8839, any model
- BladeCenter HS20, type 8678, any model
- BladeCenter HS20, type 8832, any model
- BladeCenter JS20, type 8842, any model
- BladeCenter T, type 8730, any model
- BladeCenter T, type 8720, any model
The system is configured with the following ESM options:
- Option part number 48P7054 or 13N0568, replacement part number (FRU) 26K6482 replaces 59P6620, 13N0557, or 26K6482
The 3 valid configurations follow:
- 4-port Gigabit Ethernet Switch Module option part number 48P7054, replacement part number (FRU) 59P6620
- 4-port Gigabit Ethernet Switch Module option part number 13N0568, replacement part number (FRU) 13N0557
- 4-port Gigabit Ethernet Switch Module option part number 13N0568, replacement part number (FRU) 26K6482
| Solution |
|---|
None. The D-Link ESM is functioning as designed.
| Workaround |
|---|
On each Blade, change the Auto setting for Flow Control to an active fixed setting. No change is required on the ESM. See the Recommended Procedures below for instructions.
| Additional information |
|---|
In BladeCenter, the Ethernet link between an ESM and a Blade is a midplane connection implemented in SERializer- DESerializer (SERDES) mode. Auto-Negotiation is not required for SERDES. With the D-Link ESM, the link is preconfigured to fixed one Gigabit per second speed in Full Duplex mode. The connection does not participate in Auto-Negotiation and thus does not provide the information needed by a Blade to resolve an Auto or Auto-Negotiate setting for Flow Control. At power-on the ESM signals that it is configured to a fixed 1Gb, Full Duplex setting, without invoking the Auto-Negotiation process. This tip applies only to the D-Link ESM.
Nortel and Cisco ESMs go beyond the SERDES requirements and they perform Auto-Negotiation with an ability to fall back to 1000/Full. Thus, these ESMs interoperate with Flow Control when linked to a blade that has an Auto setting.
| Recommended procedures |
|---|
To modify the setting for Flow Control on a blade running Win2000 Server, and using the Broadcom NetXtreme Gigabit Driver, perform the following procedure:
- Right click My Network Places on the Desktop.
- Left click Properties to open the Network and Dial-up Connections
- Highlight the active LAN, right click on it, and then left click on properties.
- This brings up the LAN connection Properties window.
- Left click Configure.
- This brings up the Broadcom NetXtreme Gigabit Driver window.
- Under the Advance Tab, in a column on the left side, left click Flow Control.
- The pull down value on the right shows AUTO.
- Click on the pulldown to see the options.
Auto
Disable
Rx Pause
Rx/Tx Pause
TX Pause
- Change the setting to Rx/TX Pause, and left click OK.
- Close LAN Connection Properties by left clicking OK. The setting will be saved as a nonvolatile setting.
To modify the setting for Flow Control on a blade running Linux, and using the BCM 5700 driver, perform the following procedure: The preferred method is to pass the following parameters to the driver.
auto_flow_control=0, 0 rx_flow_control=1,1 TX_flow_control=1,1
This may be done with the modules.conf file as follows:
alias eth0 bcm5700 alias eth1 bcm5700 options bcm5700 auto_flow_control=0,0 rx_flow_control=1,1 TX_flow_control=1,1
The Broadcom Flow Control options
rx_flow_control
Enables or disables receiving flow control (pause) frames.
This parameter is used together with auto_flow_control.
The valid values are:
0 pause receive disabled
1 pause receive enabled if auto_flow_control is set to 0, or pause receive advertised if auto_flow_control is set to 1 (default)
TX_flow_control
Enables or disables transmitting flow control (pause) frames.
This parameter is used together with auto_flow_control.
The valid values are:
0 pause transmit disabled
1 pause transmit enabled if auto_flow_control is set to 0, or pause transmit advertised if auto_flow_control is set to 1 (default)
auto_flow_control
Enables or disables autonegotiation of flow control. This parameter is used together with rx_flow_control and TX_flow_control to determine the advertised flow control capability.
The valid values are:
0 flow control autonegotiation disabled
1 flow control autonegotiation enabled with capability specified in rx_flow_control and TX_flow_control only valid if line_speed is set to 0 or auto_speed is set to 1 (default)
Document Location
Worldwide
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Document Information
Modified date:
29 January 2019
UID
ibm1MIGR-57465