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Managing Network Datalinks in Oracle® Solaris 11.4

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Updated: November 2020

Customizing Enhanced Transmission Selection for DCB

The default configuration is automatically set up when LLDP is enabled and DCB is supported by the underlying link. In this default configuration, the cos value 0 is assigned all of the bandwidth. However, you can use the dladm set-linkprop command to configure the cos values on a datalink to assign part of the bandwidth to that datalink.

ETS configuration and recommendation TLVs are enabled by default for a NIC. For a list of possible values for dot1-tlv, refer to Figure 1, Table 1, Optional TLV Units for an LLDP Agent.

If you want to remove the pfc TLV, type the following command:

$ lldpadm set-agenttlvprop -p dot1-tlv-=pfc agent

Setting the ETS-Related Datalink Properties

The properties of datalinks that refer to PFC information apply to the prevention of packet loss based on the priorities defined for the packets. The ETS properties relate to assigning shares of the underlying link's bandwidth based on priorities.

    DCB provides the following ETS-related properties:

  • cos – Specifies the class of service or priority of the datalink. The value of this property ranges from 0 to 7. The default value is 0. The cos value is set in the VLAN tag of the packets that are transmitted over this link.

  • ets-bw-local – Indicates the ETS bandwidth that is allocated on the transmit (Tx) side for the datalink. This property is configurable only if the underlying physical NIC has DCB capabilities and supports ETS and the link's cos property is not set to 0. You set a value for this property on a datalink by specifying the percentage of total bandwidth of the underlying physical link. The sum of the values for the ets-bw-local property for all the datalinks over the same physical NIC must not exceed 100%.

    The bandwidth percentage that is defined on ets-bw-local is not reserved only for that datalink. If the allocated bandwidth is not used, then it can be used by other datalinks on that physical NIC. Further, the bandwidth allocation is enforced only on the transmission side of the host's traffic.

  • ets-bw-remote-advice – Specifies the recommended ETS bandwidth value sent to the peer. By default, the locally configured value of the ets-bw-local property is recommended to the peer. However, you can recommend a value that is different from the ets-bw-local property by explicitly configuring the ets-bw-remote-advice datalink property.

    Configuring the ets-bw-remote-advice property is useful if the bandwidth assignment for a datalink is asymmetrical, which means that the receive (Rx) and transmit (Tx) bandwidth are different. When you explicitly set the ets-bw-remote-advice property, transmission of the ETS recommendation DCBX TLV starts automatically.

  • ets-bw-local-advice – Specifies the recommended bandwidth share for the datalink, which is sent by the peer to the local host. This is a read-only property.

  • ets-bw-remote – Specifies the bandwidth share that is configured on the peer for the datalink. This is a read-only property.

    To set the priority and to allocate a bandwidth to the VNIC, use the following commands:

  • To set the priority to the VNIC:

    $ dladm set-linkprop -p cos=value VNIC
  • To allocate a percentage of the bandwidth of the underlying physical link to a VNIC:

    $ dladm set-linkprop -p ets-bw-local=value VNIC

    The value that you assign to the ets-bw-local property represents a percentage of the total bandwidth capacity of the underlying link. The sum of all the allocated bandwidth values that you assign to the clients must not exceed 100 percent.

  • To explicitly recommend a bandwidth that is sent to the peer:

    $ dladm set-linkprop -p ets-bw-remote-advice=value VNIC

You can determine the actual bandwidth share that is implemented on the local host's datalink and the bandwidth share that is configured on the peer's datalink by using the dladm show-linkprop command. The value in the EFFECTIVE field of the output for the ets-bw-local and ets-bw-remote properties shows the actual bandwidth share implemented. For more information, see Displaying ETS Configuration Information.

For the appropriate bandwidth to be used for packets with specific priorities, symmetric or synchronized ETS information between the communicating hosts is preferable. Specifically, should be the local system that is able to adjust its bandwidth share to the value of ets-bw-local-advice. An Oracle Solaris system can automatically adjust its ETS configurations to match the ETS recommendation from the peer.

Setting ETS TLV Units

The ETS TLV (etscfg) configuration determines how the host responds to ETS recommendations from the peer. This TLV unit has only one configurable property, willing. By default, this property is set to on and enables the local host to synchronize its ETS configuration with the ETS recommendation of the remote peer.

To verify that the host can synchronize its ETS information with the ETS information of the remote peer, use the following command:

$ lldpadm show-agenttlvprop -p willing -a agent etscfg

If the willing property is set to off, type the following command to establish synchronization:

$ lldpadm set-agenttlvprop -p willing=on -a agent etscfg

To prevent synchronization of information for a specific agent, set the willing property to off as follows:

$ lldpadm set-agenttlvprop -p willing=off -a agent etscfg

where agent is the datalink on which the agent is enabled.