Subject: [core] changing block size / draft-ietf-core-block-16

From: "Kraus Achim (INST/ESY4)" <[email-masked]>
Date: Fri, 27 Feb 2015 08:36:05 +0000

Dear All,
the examples in draft-ietf-core-block-16 with changing the block size assume, that the receiver is able to process larger messages and just prefer smaller ones. For devices, which are not able to process larger messages, this approach fails. Though this case may be processed with retries, it would be clearer, if examples for those cases were added.
By the way, I would prefer a way, in which the receiver could also inform the sender, that only a smaller part of the message could be processed. For block2 it may be considered, that a client request the next smaller block only having processed the head of the first message sending the next request with num 1 (e.g. for the example in 3.1., figure 4, page 18, use for second request 2:1/0/64 (in case, only the first 64 bytes could be processes) instead of 2:2/0/64 (in case, the whole 128 bytes could be processed)). For block1 it may be considered, that a response with block num 0 and with smaller block size should indicate, that only the smaller block could be processed, and response with a block num "(request block size / preferred block size) - 1" should indicate, that the first message was processed completely, but the smaller block size is preferred by the receiver (e.g. for the example in 3.2., figure 9, page 21, use for response 1:0/1/32 (in case, only the first 32 bytes could be processes), 1:3/1/32 (in case, the whole 128 bytes could be processed)).

Mit freundlichen Grüßen / Best regards

Achim Kraus

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