Configuring Port Speed

NetVisor OS enables you to configure switch ports with different speed values up to 100 Gbps depending on the specific transceiver. For example, you must use SFP transceivers for ports configured with speeds of 1 Gbps, and SFP+ or QSFP  transceivers for ports configured with speeds of 10 Gbps or higher.

With a transceiver that is capable of breakout configuration, you can divide a 40 Gigabit Ethernet (GbE) port into four logical 10 GbE ports or a 100 Gigabit Ethernet (GbE) port into four logical 25 GbE ports. You must first disable a port before creating this configuration.

Use the port-config-modify command to configure the desired throughput on a port.

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


Modify port configuration.

Specify one among the two following parameters:

port port-list

Specify a single port or a list of ports.

Note: If more than one port is specified, the list must be comma-separated without spaces.

description description-string

Specify the port description. 

Specify any of the following options:

speed disable|10m|100m|1g|2.5g|10g|25g|40g|50g|100g

Specify the port speed. Ports configured for speeds of 1G must be equipped with SFP transceivers. Ports configured for 10G or higher must be equipped with SFP+ or QSFP+ transceivers.

egress-rate-limit unlimited

Specify an egress rate limit for the port.

eth-mode 1000base-x|sgmii|xlaui|gmii|sfi|xfi|cx|kr4|sr4|lr4|er4|cr4|cx4|kx4|caui4|kr2|er2|cr2|sr2|lr2|xlaui2|cx2|sr|lr|er|cr|kx|kr|zr|base-x|sys-default|caui|aoc|xlppi|psm4|base_t|base_cx|base_lx|base_sx

Select one of the ethernet modes from the available options. 


Specify if the port auto-negotiates the port speed with a peer.


Specify if the port forwards jumbo frames. Jumbo frames are Ethernet frames with more than 1500 bytes of payload.


Specify if the port is enabled and forwards or drops frames.

lacp-priority integer

Specify the LACP priority for the port. If you specify a low value for the priority, the port has a higher priority. This is a value between 1 and 65535.


Specify if the port reflects frames received for loopback testing.


Specify if the port connects to another Arista Networks device or is an uplink to a third-party switch or host.


Specify if you want to pause traffic on the port.

description description-string

Specify a description for the port.


Specify to use loopback or no loopback.


Specify if a VXLAN terminates on a port.


Specify if the port receives mirrored traffic only.

port-mac-address mac-address

Specify the MAC address for the physical port.

send-port send-port-number

Specify the port to send traffic.

loop-vlans vlan-list

Specifies VLANs that are looping on the network.


Specify if the port is participating in routing on the switch.


Specify if you want to delay port activation.


Specify if you want host-facing ports enabled or disabled.


Specify if you want CRC checking performed by the port. This is applicable to a switch in Virtual Wire mode. The default value is crc-check-disable.

dscp-map dscp-map name|none

Specify a DSCP map name to enable on port.


Specify if local switching is allowed on the port.

allowed-tpid vlan|q-in-q|q-in-q-old

Specify the allowed TPID in addition to 0x8100 on VLAN header


Specify if you want loop detection enabled on the port.


Specify to enable port forward correction error (FEC) mode.

For example, to configure a 40 GbE port as four 10 GbE ports, use the following command:

CLI (network-admin@Leaf1) > port-config-modify port 49-52 speed 10g

To unify the four logical ports and to set the port configuration back to 40 GbE, use the following command:

CLI (network-admin@Leaf1) > port-config-modify port 49 speed 40g