The activity performed last 20 June, was successfully completed. The switch now supports Ethernet frames of up to 9216 bytes. Increasing the part of the frame used to carry user data without increasing the header makes it possible to decrease the protocol’s “overhead”.


Ethernet devices allow you to set a parameter called “Maximum Transmission Unit” (MTU), which corresponds to the maximum frame size that the device supports. The 1985 IEEE 802.3 Ethernet standard used an MTU of 1542 bytes, allowing a payload of 1500 bytes of data in each frame. The payload is the part of the frame occupied by the data useful to the user, the remainder is occupied by the source and destination addresses and other control fields.

Increasing the MTU can be advantageous in situations when there is mass transfer of data in one direction, as in a downloadable file, for example. There are no perfect links, all have an error rate, that is, some transmitted frames arrive at the receiver with errors. If a large frame arrives incorrectly it will have to be retransmitted. Therefore, if the error rate is high, it is best to use small frames to have fewer retransmissions. Jumbo frames are only advantageous in reliable links.

With the evolution of technology, links gained reliability and error rates fell. So it is better to use large frames to gain efficiency. For this reason, the jumbo-frame was created, which makes it possible to carry around 9000 bytes of useful payload.

ANSP has been supporting jumbo frames for some time. Kyatera is being reconfigured to support them too. Reconfiguration is a fairly simple process, requiring only a few commands to be entered in the configuration. But some devices need to be rebooted to activate it.

The demand was generated by the use of USP-NAP’s Kyatera connection, as an emergency route by USP, UNESP, UFSCar and RNP. To use Kyatera to carry ANSP or RNP traffic requires the stretch to have the same characteristics as ANSP or RNP. And both work with jumbo frames.

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