> 6.Transferring Bulk Data over the GRASP - 10min > 10:55 - 11:05, by Bing Liu, draft-carpenter-anima-grasp-bulk > > [Sheng] I see use cases of this, e.g. IoT device software/firmware update. > But > I'm not sure why you have the MTU as 2000 byte? > [Bing] It is mostly for convenience of parsing the GRASP messages because > under > layer is CBOR serialization, a fixed 2000 byte is easy to identify the end > of the message.
At some point in the design of GRASP it became clear that a default maximum message size was a practical requirement. The choice of 2048 was made in draft-ietf-anima-grasp-08. Discussion thread at: https://mailarchive.ietf.org/arch/msg/anima/y-WC1sUFYJ6f_gBALzrg6M4obvE The practical impact is the buffer size you set for recvfrom(). Also, there will be a physical limit for UDP multicast. The GRASP spec says: GRASP nodes MUST be able to receive unicast messages of at least GRASP_DEF_MAX_SIZE bytes. GRASP nodes MUST NOT send unicast messages longer than GRASP_DEF_MAX_SIZE bytes unless a longer size is explicitly allowed for the objective concerned. For example, GRASP negotiation itself could be used to agree on a longer message size. So it would be quite legal for bulk transfer to negotiate a larger size. (I had forgotten that when Joel raised this issue.) Brian _______________________________________________ Anima mailing list [email protected] https://www.ietf.org/mailman/listinfo/anima
