Broadcom ISCSI offload engine defaults to DHCP enabled

Resolving The Problem

Source

RETAIN tip: H202215

Symptom

The Broadcom NetXtreme II network adapters listed in the affected items list contain a feature called internet Small Computer System Interface (iSCSI) Offload Engine to assist processing of iSCSI traffic.

When installing the Broadcom network driver package on a system running the Microsoft Windows Operating System (OS), a driver for iSCSI Offload Engine is automatically installed.

This iSCSI Offload Engine defaults to having Dynamic Host Configuration Protocol (DHCP) enabled. Therefore, if there is a DHCP server present on the network, the adapter can unexpectedly get an Internet Protocol (IP) address of its own, separate from the networking interface.

Affected configurations

The system is configured with one or more of the following IBM Options:

• NetXtreme II 1000 Express Dual Port Ethernet Adapter, Option 42C1780, replacement part number 42C1782
• NetXtreme II 1000 Express Quad Port Ethernet Adapter for IBM System x, Option 49Y4220, replacement part number 49Y4222

This tip is not system specific.

This tip is not software specific.

The iSCSI Offload Engine device driver for the Broadcom NetXtreme II Network Adapter is affected.

Broadcom NetXtreme II Network Adapter

Workaround

In order to stop the iSCSI Offload Engine from getting an IP address of its own, disable the feature.

To disable the feature, use Broadcom Advanced Control Suite (BACS) tool. The BACS tool can be installed from the Broadcom Driver CD.

Complete the following steps:

1. Click the appropriate port from the left-hand side Device Management section under "System Devices (VBD)" list.
   
   
2. Click the "Configurations" tab on the right-hand side.
   
   
3. Click "Resource Reservations" to open the list.
   
   
4. Find the "Pre-Allocated Resources" section for "iSCSI Offload Engine" and remove the check.
   
   
5. Click "Apply" to execute the change.
   
   
6. Repeat steps 1-5 for each necessary physical port.
   
   

For more details, see the "Using iSCSI" section of the User's Guide contained in the Broadcom Driver CD.

Additional information

The Broadcom NetXtreme II network adapters listed in the affected items list contain a feature called iSCSI Offload Engine, which works independently from typical Transmission Control Protocol (TCP)/IP networking traffic. A single physical port can have both functions enabled at the same time. Below are the characteristics.

Driver:
The iSCSI Offload Engine interface uses a bxois.sys driver, and networking interface uses bxnd60a.sys driver (as of Broadcom version T6.0.4.3 Driver), which are both automatically installed on a Windows OS when the Broadcom driver package installer is executed. A separate device can be identified from Windows Device Manager by searching the Storage controllers section for "Broadcom NetXtreme II C-NIC iSCSI Adapter," and the networking interface will be listed under the Network adapters section as "Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client)."

Media Access Control (MAC) Address:
The iSCSI Offload Engine interface and networking interface use a separate MAC address, which can be confirmed using the BACS tool. Typically, the MAC address is consecutive. For example, if the MAC for networking is XX-XX-XX-XX-XX-X0, then the MAC for iSCSI would be XX-XX-XX-XX-XX-X1. Some security software may detect and alert the presence of this additional MAC address.

IP Address:
The iSCSI Offload Engine interface and networking interface operate independently and will require separate IP addresses. The iSCSI Offload Engine interface defaults to DHCP enabled and will issue a DHCP Discover packet. Otherwise, a static IP address can be manually assigned from the BACS tool. Additionally, the iSCSI Offload Engine interface is not detected as a network interface, so it will not be displayed in the Windows Network Properties. It will not be displayed using the Windows ipconfig command. Use the BACS tool to verify the configuration, or check the MAC address registered on the DHCP Server.

Based on the characteristics listed above, the NetXtreme II network adapter may assign itself an additional IP address from a DHCP Server without notice. If such condition is not desired, then disable the iSCSI Offload Engine feature using the Workaround provided in this tip. Disabling the feature will unload the bxois.sys driver.

The Broadcom iSCSI Offload Engine driver for Linux Operating Systems should be manually installed and configured separately from the networking driver.