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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iSCSI Framing FormatsMike & All, We don't want this thread to be started again in this forum. For anything related to framing go to the TSWG or to the RDMA mailing list. Julo "Mike Parkhurst" <mike@integrix.com> on 10-07-2001 02:23:54 Please respond to mike@integrix.com To: tnguyen@perfisans.com, ips@ece.cmu.edu, Julian Satran/Haifa/IBM@IBMIL, steph@cs.uchicago.edu cc: Subject: RE: iSCSI Framing Formats Hello All, I've had the same thoughts after reading the spec. Pardon my lack of knowledge as to the previous discussions, but why not use a framing bit pattern as a marker? Pick some 32 bit number, anything but all zeros or ones would work, and prefix each header with it. If there is a packet loss then the receiver can scan for the next "possible" marker. Once a marker pattern is found the receiver then does a sanity check on the header. If it passes then the receiver is re-synced. If not then the search continues until a valid marker & header is found. Mike Parkhurst -----Original Message----- From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu] On Behalf Of Trang Nguyen Sent: Monday, July 09, 2001 1:44 PM To: ips@ece.cmu.edu; julian_satran@il.ibm.com; steph@cs.uchicago.edu Cc: Trang Nguyen Subject: iSCSI Framing Formats Hello everyone, I've read your discussion about how to find iSCSI PDU header from the TCP stream at the receiving end. There are 2 different approaches with various ways: 1. TCP unaware approach suggests: periodic marker, fixed length messages, byte stuffing, chunks. 2. TCP aware approach suggests: Urgent pointer, and PSH bit. I found that there are some objections about using Urgent point and PSH bit because the TCP has to be modified. The iSCSI internet draft suggests the use of periodic marker. The problem with the periodic marker in the iSCSI I-D is that both initiator and target have to agree on the marker. "In certain environments a sender not willing to supply markers to a receiver willing to accept marker MAY suffer from a considerable performance degradation." (draft-ietf-ips-iscsi-06.txt). I am just wondering if any method of iSCSI framing has been finalized yet? What is the status of this issue? Will the next version of iSCSI I-D have more information about it? Thank you in advance for your reply, Trang Nguyen
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