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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: questions/suggestions on <draft-ietf-ips-fcovertcpip-06.txt>> 1. section 4->4) Class 1 FC frames( and some signals) are not > transmitted > across an FCIP link. Since purpose of FCIP is to replace > end-to-end fiber. > So, how these frames will be transferred ? Class 1 is connection oriented and requires 100% guaranteed bandwidth the whole length of the link. TCP/IP cannot support that behavior reliably. This did not hurt anybody's feelings because class 1 is principally a legacy implementation. > > 2. section 5.2 , fig. 2 FCIP Link Model is little bit > confusing. Instead of > writing FCIP on one side and Link on other side, it will be > good if FCIP > Link is written both side. > The intent here is that the IP network as well as the two wires to the FC Fabric be interpreted as a single link. > 3. section 5.6.2.1 and 5.6.2.2. If someone is doing TCP > checksum validation, > is it required to do 5.6.2.2 checks ? At least test j) is not > required ? > The required checking is specified because the TCP checksum validation (which of course is assumed to be present) has proven less than perfectly reliable in some environments. The tests are required according to the explanations. Verification of length and length redundancy is required. At least some other verifications are a very good idea. > 4. Once TCP payload will have only one FC frame or it can > have multiple FC > frame ? Its not mentioned anywhere, but from the section > 5.6.2.2 and 5.6.2.3 > it seems to me that it can have multiple FC frame ? There is no relationship between a TCP payload or segment and the FC frame boundaries. That is the nice thing about TCP. It simply delivers a string of reasonably well checked bytes in the proper order and lets the upper layers choose what to do with them. As a result, a TCP payload may have a fraction of a frame, fractions of two frames, fractions of two frames and one or more whole frames, exactly one whole frame, or multiple whole frames. FCIP does not care, as long as the transmission of a TCP payload is not unduly held up waiting for enough information to make it a certain size. Realistically, I would expect that many implementations will at least start a TCP segment on an encapsulated frame boundary, but only end on a frame boundary if there was no additional information to throw into the segment, but that is NOT part of the architecture.
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