bonding: add weight support for active-backup mode

Not all interfaces have the same characteristics within the bonding group.
For active-backup mode, we should do our best to select the slave that
performs the best as the primary slave. We already did that by preferring
the slave that is local numa. Sometimes, this is not enough. For example,
when all are local numas, the selection is arbitrary. Some slave interfaces
may have higher speed or better qos than the others. But this is hard to
infer.

One rule does not fit all. So we let the operator to optionally specify the
weight for each slave interface. Our primary slave selection rule is now
1. biggest weight
2. is local numa
3. current primary slave (to avoid churn)
4. lowest sw_if_index (for deterministic behavior)

This selection rule only applies to active-backup mode which only one slave
is used for forwarding traffic until it becomes unreachable. At that time,
the next "best" slave candidate is automatically promoted. The slaves are
sorted according to the preference rule when they are up. So there is no need
to find the next best candidate when the primary slave goes down.

Another good thing about this rule is when the down slave comes back up, it
is selected as the primary slave again unless there is indeed a "better"
slave than this down slave that were added during that period.

To set the weight for the slave interface, do this after the interface is
enslaved

set interface bond <interface-name> weight <value>

Type: feature

Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: I59ced6d20ce1dec532e667dbe1afd1b4243e04f9

1 files changed, 19 insertions, 5 deletions

diff --git a/src/vnet/bonding/node.h b/src/vnet/bonding/node.h
index 1ad19dec872..1479209369a 100644
--- a/src/vnet/bonding/node.h
+++ b/src/vnet/bonding/node.h
@@ -110,6 +110,15 @@ typedef struct
   clib_error_t *error;
 } bond_detach_slave_args_t;
 
+typedef struct
+{
+  u32 sw_if_index;
+  u32 weight;
+  /* return */
+  int rv;
+  clib_error_t *error;
+} bond_set_intf_weight_args_t;
+
 /** BOND interface details struct */
 typedef struct
 {
@@ -130,6 +139,8 @@ typedef struct
   u8 interface_name[64];
   u8 is_passive;
   u8 is_long_timeout;
+  u8 is_local_numa;
+  u32 weight;
   u32 active_slaves;
 } slave_interface_details_t;
 
@@ -159,11 +170,6 @@ typedef struct
   u8 mode;
   u8 lb;
 
-  /* This flag works for active-backup mode only
-     and marks if the working port is local numa. */
-  u8 is_local_numa;
-  /* current working sw_if_index in active-bakeup mode. */
-  u32 sw_if_index_working;
   /* the last slave index for the rr lb */
   u32 lb_rr_last_index;
 
@@ -239,6 +245,9 @@ typedef struct
   /* neighbor vlib hw_if_index */
   u32 hw_if_index;
 
+  /* weight -- valid only for active backup */
+  u32 weight;
+
   /* actor does not initiate the protocol exchange */
   u8 is_passive;
 
@@ -336,6 +345,9 @@ typedef struct
 
   /* pdu sent */
   u64 marker_pdu_sent;
+
+  /* slave is numa node */
+  u8 is_local_numa;
 } slave_if_t;
 
 typedef void (*lacp_enable_disable_func) (vlib_main_t * vm, bond_if_t * bif,
@@ -398,6 +410,8 @@ void bond_disable_collecting_distributing (vlib_main_t * vm,
 void bond_enable_collecting_distributing (vlib_main_t * vm, slave_if_t * sif);
 u8 *format_bond_interface_name (u8 * s, va_list * args);
 
+void bond_set_intf_weight (vlib_main_t * vm,
+			   bond_set_intf_weight_args_t * args);
 void bond_create_if (vlib_main_t * vm, bond_create_if_args_t * args);
 int bond_delete_if (vlib_main_t * vm, u32 sw_if_index);
 void bond_enslave (vlib_main_t * vm, bond_enslave_args_t * args);