Performance optimization¶

The following recommendations apply to all types of nodes in the Mirantis OpenStack for Kubernetes (MOSK) clusters.

Jumbo frames¶

To improve the goodput, we recommend that you enable jumbo frames where possible. The jumbo frames have to be enabled on the whole path of the packets traverse. If one of the network components cannot handle jumbo frames, the network path uses the smallest MTU.

Bonding¶

To provide fault tolerance of a single NIC, we recommend using the link aggregation, such as bonding. The link aggregation is useful for linear scaling of bandwidth, load balancing, and fault protection. Depending on the hardware equipment, different types of bonds might be supported. Use the multi-chassis link aggregation as it provides fault tolerance at the device level. For example, MLAG on Arista equipment or vPC on Cisco equipment.

The Linux kernel supports the following bonding modes:

active-backup
balance-xor
802.3ad (LACP)
balance-tlb
balance-alb

Since LACP is the IEEE standard 802.3ad supported by the majority of network platforms, we recommend using this bonding mode. Use the Link Aggregation Control Protocol (LACP) bonding mode with MC-LAG domains configured on ToR switches. This corresponds to the 802.3ad bond mode on hosts.

Additionally, follow these recommendations in regards to bond interfaces:

Use ports from different multi-port NICs when creating bonds. This makes network connections redundant if failure of a single NIC occurs.
Configure the ports that connect servers to the PXE network with PXE VLAN as native or untagged. On these ports, configure LACP fallback to ensure that the servers can reach DHCP server and boot over network.

Spanning tree portfast mode¶

Configure Spanning Tree Protocol (STP) settings on the network switch ports to ensure that the ports start forwarding packets as soon as the link comes up. It helps avoid iPXE timeout issues and ensures reliable boot over network.