Enabling Jumbo Frame Support

Jumbo frames are (oversized) Ethernet frames with a size greater than 1518 bytes (including the Ethernet header and FCS) or 1522 bytes (when a VLAN tag is present).

Different vendors may support different maximum frame sizes for jumbos, as the IEEE standard does not cover jumbo frames (except for baby giants). Typically jumbo frames are described with the maximum payload length they support, namely, the Maximum Transmission Unit (MTU). It is common for platforms (including servers) to support jumbo frames with (at least) an MTU of 9K bytes. 1 K usually corresponds to 1000 (but may also equate to 1024 on some platforms), so that means that the MTU is 9000 (or 9216) bytes.

When you enable the jumbo frame feature on a port on Arista switches, the port can accept and forward jumbo frames. This feature is meant to optimize server-to-server performance (by minimizing the CPU processing overhead for large block transfers).

By default, jumbo frames are disabled on NetVisor OS and so the default Ethernet MTU for all switch ports is 1500 bytes. When you enable the jumbo frame feature on a port, the MTU size is increased to accept 9K byte frames on that port.

The larger MTU supported on Arista switches helps on transport links to be able to deal with the transport overhead (for example, with the VXLAN and vLE functionalities described in the Configuring VXLAN and Configuring Advanced Layer 2 Transport Services sections).

To enable jumbo frame support, add the jumbo parameter to the port-config-modify command: 

CLI (network-admin@switch) > port-config-modify port 1 jumbo 

To enable jumbo frame support on trunk ports, add the jumbo parameter to the trunk-modify or trunk-create commands:

CLI (network-admin@switch) > trunk-modify name trunk1 jumbo