Concept Guide

11 Data Center Bridging (DCB)...................................................................................................................... 251
Ethernet Enhancements in Data Center Bridging...................................................................................................... 251
Priority-Based Flow Control................................................................................................................................... 252
Enhanced Transmission Selection..........................................................................................................................253
Data Center Bridging Exchange Protocol (DCBx)...............................................................................................254
Data Center Bridging in a Trac Flow.................................................................................................................. 255
Enabling Data Center Bridging.....................................................................................................................................255
DCB Maps and its Attributes................................................................................................................................. 256
Data Center Bridging: Default Conguration..............................................................................................................257
Conguring Priority-Based Flow Control.................................................................................................................... 257
Conguring Lossless Queues................................................................................................................................. 258
Conguring PFC in a DCB Map................................................................................................................................... 260
PFC Conguration Notes....................................................................................................................................... 260
PFC Prerequisites and Restrictions........................................................................................................................261
Applying a DCB Map on a Port.....................................................................................................................................261
Conguring PFC without a DCB Map.........................................................................................................................262
Conguring Lossless QueuesExample:..................................................................................................................262
Conguring PFC Asymmetric.......................................................................................................................................263
Priority-Based Flow Control Using Dynamic Buer Method....................................................................................264
Pause and Resume of Trac..................................................................................................................................264
Buer Sizes for Lossless or PFC Packets............................................................................................................ 264
Behavior of Tagged Packets.........................................................................................................................................265
Conguration Example for DSCP and PFC Priorities................................................................................................265
SNMP Support for PFC and Buer Statistics Tracking............................................................................................266
Performing PFC Using DSCP Bits Instead of 802.1p Bits.........................................................................................266
PFC and ETS Conguration Examples........................................................................................................................267
Using PFC to Manage Converged Ethernet Trac...................................................................................................267
Operations on Untagged Packets................................................................................................................................ 267
Generation of PFC for a Priority for Untagged Packets...........................................................................................268
Congure Enhanced Transmission Selection..............................................................................................................268
ETS Prerequisites and Restrictions....................................................................................................................... 268
Creating an ETS Priority Group..............................................................................................................................268
ETS Operation with DCBx...................................................................................................................................... 270
Conguring Bandwidth Allocation for DCBx CIN.................................................................................................270
Conguring ETS in a DCB Map...............................................................................................................................271
Hierarchical Scheduling in ETS Output Policies......................................................................................................... 272
Using ETS to Manage Converged Ethernet Trac................................................................................................... 273
Applying DCB Policies in a Switch Stack.................................................................................................................... 273
Congure a DCBx Operation........................................................................................................................................ 273
DCBx Operation....................................................................................................................................................... 273
DCBx Port Roles.......................................................................................................................................................274
DCB Conguration Exchange.................................................................................................................................275
Conguration Source Election................................................................................................................................275
Propagation of DCB Information............................................................................................................................276
Auto-Detection and Manual Conguration of the DCBx Version.......................................................................276
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