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Data length extension

Bene

Hi,

what is the Maximum packet size, if I use Data length extension?

How ist it ceonnected to the ATT_MTU size?

thank you in advanced

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    PDU size is payload of each packet on Link Layer. ATT_MTU is unit on upper layer called Attribute Protocol. So ATT_MTUs are transported over LL PDUs, there is some overhead of these layers (as well as intermediate layers like L2CAP. In general you can see them independent and it works with sizes which are not aligned (you can transport up to 512B of ATT_MTU and all that happening over default "short" Link Layer packets. However if you want optimal throughput you need to understand flow of your application (half-duplex/full duplex, what are typical message sizes on APP layer which can be put to lower layers like GATT/ATT at once etc.) Read more in this blog post (in the middle of article there is elaboration about PDU and ATT_MTU).

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    PDU size is payload of each packet on Link Layer. ATT_MTU is unit on upper layer called Attribute Protocol. So ATT_MTUs are transported over LL PDUs, there is some overhead of these layers (as well as intermediate layers like L2CAP. In general you can see them independent and it works with sizes which are not aligned (you can transport up to 512B of ATT_MTU and all that happening over default "short" Link Layer packets. However if you want optimal throughput you need to understand flow of your application (half-duplex/full duplex, what are typical message sizes on APP layer which can be put to lower layers like GATT/ATT at once etc.) Read more in this blog post (in the middle of article there is elaboration about PDU and ATT_MTU).

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