iSCSI: Parameter negotiation Q

[Michael Schoberg <michael_schoberg@cnt.com>]

Title:

11.14  FirstBurstLength

   Use: LO
   Senders: Initiator and Target
   Scope: SW
   Irrelevant when: SessionType=Discovery
   Irrelevant when: ( InitialR2T=Yes and ImmediateData=No )

   FirstBurstLength=<numerical-value-512-to-(2**24-1)>

   Default is 65536 (64 Kbytes).
   Result function is Minimum.

   The initiator and target negotiate the maximum amount in bytes of
   unsolicited data an iSCSI initiator may send to the target during the
   execution of a single SCSI command. This covers the immediate data
   (if any) and the sequence of unsolicited Data-Out PDUs (if any) that
   follow the command.

   FirstBurstLength MUST NOT exceed MaxBurstLength.

I understand we're past the revision stage on iSCSI, but I'm confused by some of the negotiation logic.  If FirstBurstLength only relates to the number of bytes Initiator->Target, why would there be a need to negotiate the value versus just having the target declare a maximum (if not equal to the default)?

Thanks.