Troubleshooting
Problem
The default maximum frame size for the Broadcom sideband interface is 1514 bytes in a Microsoft Windows environment. This frame size does not account for the Virtual LAN (VLAN) header which is 4 byte. The correct maximum frame size should be 1518 bytes.The sideband interface is used by functions such as Serial Over LAN (SOL) and remote systems management using the IPMI protocol. This creates an issue in a blade environment while trying to mount remote media such as a CD-ROM using the Concurrent KVM BladeCenter Feature Card, Option 26k5939. The CD-ROM mount is usually successful but a session hang condition can occur while attempting to access the CD-ROM data.
Resolving The Problem
Source
RETAIN tip: H193209
Symptom
The default maximum frame size for the Broadcom sideband interface is 1514 bytes in a Microsoft Windows environment.
This frame size does not account for the Virtual LAN (VLAN) header which is 4 bytes. The correct maximum frame size should be 1518 bytes. The sideband interface is used by functions such as Serial Over LAN (SOL) and remote systems management using the IPMI protocol.
This creates an issue in a blade environment while trying to mount remote media such as a CD-ROM using the Concurrent KVM BladeCenter Feature Card, Option 26K5939. The CD-ROM mount is usually successful but a session hang condition can occur while attempting to access the CD-ROM data.
Affected configurations
The system may be any of the following IBM servers:
- BladeCenter HS12, type 8014, any model
- BladeCenter HS12, type 8028, any model
The system is configured with one or more of the following IBM Options:
- BladeCenter Concurrent KVM Feature Card, Option 26K5939
The system is configured with at least one of the following:
- Microsoft Windows 2000 Advanced Server, any service pack
- Microsoft Windows 2000 Datacenter Server, any service pack
- Microsoft Windows 2000 Professional, any service pack
- Microsoft Windows 2000 Server, any service pack
- Microsoft Windows 2000 Server 64-bit Limited Edition, any service pack
- Microsoft Windows 2003 Server, any service pack
- Microsoft Windows 2003 Server for 32-bit Servers, any service pack
- Microsoft Windows 2003 Server for 64-bit Servers, any service pack
- Microsoft Windows 2003 Server, Datacenter Edition, any service pack
- Microsoft Windows 2003 Server, EE x64, any service pack
- Microsoft Windows 2003 Server, x64 Edition, any service pack
- Microsoft Windows Server 2008, Datacenter 32-bit, any service pack
- Microsoft Windows Server 2008, Datacenter 64-bit, any service pack
- Microsoft Windows Server 2008, Enterprise 32-bit, any service pack
- Microsoft Windows Server 2008, Enterprise 64-bit, any service pack
- Microsoft Windows Server 2008, Standard 32-bit, any service pack
- Microsoft Windows Server 2008, Standard 64-bit, any service pack
Note: This does not imply that the network operating system will work under all combinations of hardware and software.
Please see the compatibility page for more information:
Solution
The issue can be avoided by using the workaround described.
This behavior will be corrected in a future release.
The target date for this release is scheduled for Third Quarter 2008.
The file will be available from the IBM System x Support web site.
Workaround
The issue can be avoided by enabling either jumbo frames or Quality of Service (QoS) options in the Advanced Properties section of the Microsoft Windows drivers. The QoS configuration item is named QoS in Microsoft Windows 2003 and Priority and VLAN in Microsoft Windows 2008.
Additional information
In Linux environments and in operating system absent environments the maximum frame size (MTU) for the sideband interface is properly set to 1518 bytes. In the Microsoft Windows environment the MTU for the sideband interface is improperly set to 1514 bytes. The session hang happens because the 1514 byte frames with VLAN headers (totaling 1518 bytes) are being rejected by the ethernet controller because they are targeted for the sideband interface and they exceed the 1514 size limit. When enough of these frames are rejected the sideband session used to communicate with the CD-ROM is terminated.
The issue does not affect ethernet traffic directed to the operating system, only the ethernet traffic directed to the sideband interface. The workaround is effective because it will cause the MTU size in the ethernet controller to be updated to the proper size for both the operating system traffic and the sideband traffic.
Document Location
Worldwide
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Document Information
Modified date:
29 January 2019
UID
ibm1MIGR-5075275