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CCIE SAN Written Study-group Session #2. 12/4/2009. Agenda. FC-0: Physical interface FC-1: Encoding and decoding, Ordered Sets FC-2: Framing protocol Link control and basic/extended link services Basic link services and extended link services. Fibre Channel Protocol Architecture.
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CCIE SAN Written Study-group Session #2 12/4/2009
Agenda • FC-0: Physical interface • FC-1: Encoding and decoding, Ordered Sets • FC-2: Framing protocol • Link control and basic/extended link services • Basic link services and extended link services
Fibre Channel Protocol Architecture • FICON/ESCON • VI (virtual interface) • IP ULP(Upper Level Protocol) ULP: SCSI-3 • FC-VI • IPFC FC-4 : SCSI-3 Mapping (SCSI-FCP) • Common services FC Basic link services FC Extended link services FC-3 • Exchange and Sequence management • Frame Structure • Classes of service • Flow control FC-2 • 8b/10b encode/decode • Ordered sets FC-1 • Physical interface • Optical and Electrical interfaces • Cables, connectors, etc FC-0
FC-1: Encoding and decoding, Ordered Sets, Link initialization • Bits/Bites, and Words • Word = 4 byte • After encoding, 4 byte becomes 40 bits • Encoding why? • Clock recovery • DC balance • Special characters different from data (D vs K characters) • Detect most of transmission errors • 8b/10b • 8 byte split into two sub-blocks • Low-order 5 bits (xx) and high-order 3 bits (y) • This becomes D/Kxx.y • Error Detection • Code violation (bit flipping) • Disparity Errors (must maintain dc parity)
FC-1: Encoding and decoding, Ordered Sets • Transmission word (4 byte) = Invalid word, ordered set, or data word • Ordered set (always starts with K28.5 + 3 Data byte) • Frame delimeter (start of frame, end of frame): identifies start of end of frames • SoF, EoF (different kinds) • Primitive signal (fill words, non-fill word): indicates events at the sending port • Fill words: ILDE, ARB • Non-Fill words: R_RDY, VC_RDY, OPN, CLS, DHD, BB_SCs, BB_SCr • Primitive sequences: used to indicate states or conditions and normally transmitted continuously • NOS, OLS, LR, LRR, LIP, LPB, LPE
FC-2: Framing protocol • Major functions • Management of login sessions between ports • Before any FC-4 ULPtrasactions, two ports must establish a login session • Management of transactions by use of the Exchange • Mechanism that two FC ports use to identify and manage a set of related Information Units (IU) – SCSI command, SCSI data, and SCSI status • Transfer of IU (Information Units) by use of Sequence of frames • There exists one-to-one mapping between FC-4 IU and FC-2 Sequences • Sequence management must break IU into 2112 max FC frame • SEQ_ID remains the same, but SEQ_CNT varies • Frame formats and structure • Frame Header : R_CTL determines 4 major Frame types as following • FC-4 device data, Extended link data, basic link data, link control frames
FC-2: Framing protocol • Major functions • flow control and credit • End to End credit: ACK-0, ACK-1 • Buffer to buffer credit(R_RDY): base and alternate methods • Class of service • Class1, Class2, Class3, Class6, Intermix (allow Class2 and Class3 to share)
Link control • Link Control: FC defines multiple link control functions that are used to manage the link and provide confirmation of deliver or notification of non-delivery • Basically provides 3 functions • Link continue (ACK) • Link response (Accept or reject) • Link control (command to initiate low-level action at the dst port) • ACK, F_BSY, P_BSY, F_RJT and PRJT, LCR, NTY, END
Basic Link services • Basic Link Data frames are used to transport Basic Link Services. Basic Link services have a number of unique characteristics. Among them are: • Basic Link Services can be issued within an existing sequence or exchange • Basic Link Data frames have no payload • Basic Link Services are clearly exempted from login requirements • Basic Link Services are generally used to manage existing sequences or exchanges. For example, • ABTS provides a mechanism to abort a sequence or exchange • BA_ACC is a single frame response that notifies the sender that command has been completed by the recipient • BA_RJT • NOP
Extended Link services • Extended Link Data frames are used to transport Extended Link Services. Unlike Basic Link Services, Extended Link Services operate within their own exchange and follow normal exchange and sequence rules. • LS_JST, LS_ACC, PLOGI, FLOGI, LOGO, ABTX, PRLO, PRLO, FDSC, RSCN, SCR
Classes • Class1 • End-to-end • Circuit-based • Class2 • End-to-end, buffer-to-buffer • Relible packet-switched • Class3 • Buffer-to-buffer • Unreliable packet-switched • Intermix • Allows class2 and class3 to trickle through • Class6 • Class1 + Multicast server
Errors timer values • R_T_TOV (Receiver Transmitter Timeout Value) • loss of synchronization • 100 msec • E_T_TOV(Error Detect Timeout Value) • Timeout value events and responses at the Sequence level • 2 seconds • R_A_TOV (Resource Allocation Timeout Value) • To determine how long to hold resources with a failed sequence or exchange • CR_TOV (Connection Request Timeout Value) • 4th timer to define how long the fabric can hold a class-1 request