Users Guide

Broadcom NetXtreme-E-UG304-2CS
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NetXtreme-E User Guide User Guide for Dell Platforms
12.4 Reducing NIC Memory Consumption with NPAR
The default value of receive buffers was selected to work well for typical configurations. If you have many NICs in a system,
have enabled NPAR on multiple NICs, or if you have only a small amount of RAM, you may see a Code 12 yellow bang in
the Device Manager for some of the NICs. Code 12 means that the driver failed to load because there were not enough
resources. In this case, the resource is a specific type of kernel memory called Non-Paged Pool (NPP) memory.
If you are getting a Code 12, or for other reasons wish to reduce the amount of NPP memory consumed by the NIC:
 Reduce the number of RSS queues from the default of 8 to 4 or 2. Each RSS queue has its own set of receive buffers
allocated, so reducing the number of RSS queues reduces the allocated NPP memory. There can be performance
implications from reducing the number of RSS queues, as fewer cores participate in processing receive packets from
that NIC. Per processor CPU utilization should be monitored to ensure that there are no “hot” processors after this
change.
 Reduce memory allocation by reducing the number of receive buffers allocated. The default value of 0 means the driver
should automatically determine the number of receive buffers. For typical configurations, a setting of 0 (=auto) maps to
XXXX receive buffers per queue. You can choose a smaller value such as 1500, 1000, or 500. (The value needs to be
in multiples of 500 between the range of 500 and 15000.) As mentioned above, a smaller number of receive buffers
increases the risk of packet drop and a corresponding impact to packet retransmissions and decreased throughput.
The parameters “Maximum Number of RSS Queues” and “Receive Buffers (0=Auto)” can be modified using the Advanced
properties tab for each NIC in the Device Manager. If you want to modify multiple NICs at the same time, it is faster to use
the Set-NetAdapterAdvancedProperty PowerShell cmdlet. For example, to assign two RSS queues for all NICs in a system
whose NIC name starts with “Sl”, run the following command:
Set-NetAdapterAdvancedProperty Sl* -RegistryKeyword *NumRSSQueues -RegistryValue 2
Similarly, to set the number of Receive buffers to 1500, run the following command:
Set-NetAdapterAdvancedProperty Sl* -RegistryKeyword *ReceiveBuffers -RegistryValue 1500
For an overview of how to use PowerShell to modify NIC properties, see Microsoft.com.
13 Tunneling Configuration Examples
Broadcom BCM5741X and BCM5751X devices support VXLAN, GRE, and IP-in-IP tunneling offloads. This section provides
tunnelling configuration examples
13.1 Network Diagram
The test network shown in Table 38 uses one Linux server with one two port Ethernet adapter. SR-IOV is enabled in the
adapter and two VFs are instantiated on the first port. A VF from the second port is exposed to the third VM (see SR-IOV –
Configuration and Use Case Examples for information on SR-IOV bring up).