[cbf] Add class-based forwarding support (sonic-net#1963)

* [cbf] Added initial CBF support (#2)

* Added CBF NHG support to NhgOrch
* Added NhgMapOrch to handle DSCP_TO_FC and EXP_TO_FC tables
* Added UT for the new NhgOrch function and NhgMapOrch

Support sonic-net/SONiC#796

Co-authored-by: Alexandru Banu <v-albanu@microsoft.com>

Author: TACappleman

doc/Configuration.md

@@ -1129,6 +1129,8 @@ name as object key and member list as attribute.
         "pfc_enable": "3,4", 
         "pfc_to_queue_map": "AZURE", 
         "dscp_to_tc_map": "AZURE",
+        "dscp_to_fc_map": "AZURE",
+        "exp_to_fc_map": "AZURE",
         "scheduler": "scheduler.port"
     }
   }

doc/swss-schema.md

@@ -194,6 +194,28 @@ and reflects the LAG ports into the redis under: `LAG_TABLE:<team0>:port`
     mpls_nh       = STRING                   ; Comma-separated list of MPLS NH info.
     weight        = weight_list              ; List of weights.
 
+---------------------------------------------
+### CLASS_BASED_NEXT_HOP_GROUP_TABLE
+    ;Stores a list of groups of one or more next hop groups used for class based forwarding
+    ;Status: Mandatory
+    key           = CLASS_BASED_NEXT_HOP_GROUP_TABLE:string ; arbitrary index for the next hop group
+    members       = NEXT_HOP_GROUP_TABLE.key ; one or more separated by ","
+    selection_map = FC_TO_NHG_INDEX_MAP_TABLE.key ; the NHG map to use for this CBF NHG
+
+---------------------------------------------
+### FC_TO_NHG_INDEX_MAP_TABLE
+    ; FC to Next hop group index map
+    key                    = "FC_TO_NHG_INDEX_MAP_TABLE:"name
+    fc_num = 1*DIGIT ;value
+    nh_index  = 1*DIGIT;  index of NH inside NH group
+
+    Example:
+    127.0.0.1:6379> hgetall "FC_TO_NHG_INDEX_MAP_TABLE:AZURE"
+     1) "0" ;fc_num
+     2) "0" ;nhg_index
+     3) "1"
+     4) "0"
+
 ---------------------------------------------
 ### NEIGH_TABLE
     ; Stores the neighbors or next hop IP address and output port or
@@ -321,6 +343,41 @@ and reflects the LAG ports into the redis under: `LAG_TABLE:<team0>:port`
      9) "4"
     10) "8"
 
+### DSCP_TO_FC_TABLE_NAME
+    ; dscp to FC map
+    ;SAI mapping - qos_map object with SAI_QOS_MAP_ATTR_TYPE == sai_qos_map_type_t::SAI_QOS_MAP_TYPE_DSCP_TO_FORWARDING_CLASS
+    key        = "DSCP_TO_FC_MAP_TABLE:"name
+    ;field       value
+    dscp_value = 1*DIGIT
+    fc_value   = 1*DIGIT
+
+    Example:
+    127.0.0.1:6379> hgetall "DSCP_TO_FC_MAP_TABLE:AZURE"
+     1) "0" ;dscp
+     2) "1" ;fc
+     3) "1"
+     4) "1"
+     5) "2"
+     6) "3"
+     7)
+---------------------------------------------
+### EXP_TO_FC_MAP_TABLE
+    ; dscp to FC map
+    ;SAI mapping - qos_map object with SAI_QOS_MAP_ATTR_TYPE == sai_qos_map_type_t::SAI_QOS_MAP_TYPE_MPLS_EXP_TO_FORWARDING_CLASS
+    key            = "EXP_TO_FC_MAP_TABLE:"name
+    ;field           value
+    mpls_exp_value = 1*DIGIT
+    fc_value       = 1*DIGIT
+
+    Example:
+    127.0.0.1:6379> hgetall "EXP_TO_FC_MAP_TABLE:AZURE"
+     1) "0" ;mpls_exp
+     2) "1" ;fc
+     3) "1"
+     4) "1"
+     5) "2"
+     6) "3"
+
 ---------------------------------------------
 ### SCHEDULER_TABLE
     ; Scheduler table

orchagent/Makefile.am

@@ -3,7 +3,8 @@ INCLUDES = -I $(top_srcdir)/lib \
            -I $(top_srcdir)/warmrestart \
            -I flex_counter \
            -I debug_counter \
-           -I pbh
+           -I pbh \
+           -I nhg
 
 CFLAGS_SAI = -I /usr/include/sai
 
@@ -40,7 +41,10 @@ orchagent_SOURCES = \
             orchdaemon.cpp \
             orch.cpp \
             notifications.cpp \
-            nhgorch.cpp \ 
+            nhgorch.cpp \
+            nhgbase.cpp \
+            cbf/cbfnhgorch.cpp  \
+            cbf/nhgmaporch.cpp \
             routeorch.cpp \
             mplsrouteorch.cpp \
             neighorch.cpp \