Datasheet

40G Cabling Technical Q&A Document
www.arista.com+ +
9+
Arista 40GbE Product Configuration:
Q. How do you change the QSFP+ ports to support 10G or 40G mode?
A. On all Arista switches with 40GbE ports the QSFP+ ports can support 4x10G or 1x40G on any
port (independently configurable).
By default the QSFP+ ports are setup as 4x10G as below:
Et52/1 notconnect 1 full 10G Not Present
Et52/2 notconnect 1 full 10G Not Present
Et52/3 notconnect 1 full 10G Not Present
Et52/4 notconnect 1 evi full 10G Not Present
To configure them for 1x40G mode use the command:
(config)#int et 52/1
(config-if-Et52/1-4)#speed forced 40gfull
You may see warnings if the transceivers are missing.
! Warning: Transceiver for interface Et52/1 is not present. Cannot verify compatibility of speed and duplex settings.
! Warning: Transceiver for interface Et52/2 is not present. Cannot verify compatibility of speed and duplex settings.
! Warning: Transceiver for interface Et52/3 is not present. Cannot verify compatibility of speed and duplex settings.
! Warning: Transceiver for interface Et52/4 is not present. Cannot verify compatibility of speed and duplex settings.
The output of show commands will now reflect 40G as a speed.
Et52/1 notconnect 1 full 40G Not Present
Et52/2 notconnect 1 full 40G Not Present
Et52/3 notconnect 1 full 40G Not Present
Et52/4 notconnect 1 full 40G Not Present
Inserting a suitable 40G transceiver or cable will bring the ports up in the “40G” mode. The other
end will be another 40G device.
To configure the port for 4x10G mode reset it to the default and let it negotiate at 10G
(config-if-Et52/1-4)#no speed
Next, use the same optics with a splitter cable, and a 10G SFP+ (SR or SRL) at the other end.
Alternatively using copper cables and swap the QSFP-QSFP for a QSFP-4SFP+.
NOTE: In 4.7.x releases this required a platform command:
switch(config)#platform trident qsfp mode 40G
After this command the interfaces need to be shut/no shut.