Troubleshooting
Problem
IBM WebSphere Load Balancer on Linux® server requires special configuration.
Symptom
All or some client connections fail.
Resolving The Problem
Certain offload features of the Load Balancer's network interface on Linux must be disabled. In general, the checksum offload feature, large send, and large receive must be disabled. The names of these settings differ depending on the network interface and linux distribution.
ethtool -K devname rx off
ethtool -K devname tx off
ethtool -K devname tso off
ethtool -K devname lro off
The devname parameter is the network interface name. If the large send or large receive setting are not disabled, the Load Balancer indicates discarded packets. The document, IBM WebSphere Load Balancer forwarding packet statistics, provides more information about discarded packets. The Load Balancer cannot detect errors that occur when checksum offload is not disabled. For more information about detecting errors from incorrect packet checksums, see Checksum Problems with the Load Balancer for more information.
Packets forwarded by the Load Balancer with MAC forwarding to Linux® backend servers, require you ARP suppression and reverse path filtering settings on the backend server. ARP suppression and reverse path filtering settings are explained: Loopback Aliasing Alternatives when using MAC Forwarding for WebSphere Edge Load Balancer on Linux
If the Load Balancer is installed on the Linux for zSeries, the configuration depends on the configured OSA layer. A layer2 configuration is recommended: Use layer2 OSA with Load Balancer for the IPv4 and IPv6 protocols. A layer3 configuration can be used but requires more configuration: see IBM WebSphere Load Balancer in layer3 network mode on Linux for System z.
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Document Information
Modified date:
02 January 2022
UID
swg21384321