ip: Router ID included in flow hash

Type: feature

A device/router needs to have a unique ID which is included in the flow
has so that flows are not polarised through the network, i.e. each deice
in the network chooses the same nth link for the same flow.

Signed-off-by: Neale Ranns <neale@graphiant.com>
Change-Id: I963e03674adbb085902b4084fdc4886b88f5734c

9 files changed, 61 insertions, 7 deletions

diff --git a/src/vnet/ip/ip.api b/src/vnet/ip/ip.api
index f201ffbd8a6..3072e3e7c63 100644
--- a/src/vnet/ip/ip.api
+++ b/src/vnet/ip/ip.api
@@ -20,7 +20,7 @@
     called through a shared memory interface.
 */
 
-option version = "3.0.2";
+option version = "3.0.3";
 
 import "vnet/interface_types.api";
 import "vnet/fib/fib_types.api";
@@ -277,6 +277,20 @@ autoreply define set_ip_flow_hash_v2
   vl_api_ip_flow_hash_config_t flow_hash_config;
 };
 
+/** \brief Set the ip flow hash router ID
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param router_id - The ID of the router. Mixed into the hash.
+                       Used to prevent polarisation across a network,
+                       since each router is assumed to have a different ID
+*/
+autoreply define set_ip_flow_hash_router_id
+{
+  u32 client_index;
+  u32 context;
+  u32 router_id;
+};
+
 /** \brief IPv6 interface enable / disable request
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
diff --git a/src/vnet/ip/ip.c b/src/vnet/ip/ip.c
index f2475335463..5d0c7707dd3 100644
--- a/src/vnet/ip/ip.c
+++ b/src/vnet/ip/ip.c
@@ -16,6 +16,8 @@
 #include <vnet/ip/ip.h>
 #include <vnet/fib/fib_table.h>
 
+u32 ip_flow_hash_router_id;
+
 u8
 ip_is_zero (ip46_address_t * ip46_address, u8 is_ip4)
 {
@@ -203,6 +205,12 @@ ip_flow_hash_set (ip_address_family_t af, u32 table_id, u32 flow_hash_config)
   return 0;
 }
 
+void
+ip_flow_hash_router_id_set (u32 router_id)
+{
+  ip_flow_hash_router_id = router_id;
+}
+
 u8 *
 format_ip_address_family (u8 * s, va_list * args)
 {
diff --git a/src/vnet/ip/ip.h b/src/vnet/ip/ip.h
index 1789fa1a659..6d822d29dbe 100644
--- a/src/vnet/ip/ip.h
+++ b/src/vnet/ip/ip.h
@@ -278,8 +278,6 @@ u8 ip_is_local (u32 fib_index, ip46_address_t * ip46_address, u8 is_ip4);
 void ip_copy (ip46_address_t * dst, ip46_address_t * src, u8 is_ip4);
 void ip_set (ip46_address_t * dst, void *src, u8 is_ip4);
 
-int ip_flow_hash_set (ip_address_family_t af, u32 table_id,
-		      flow_hash_config_t flow_hash_config);
 void ip_feature_enable_disable (ip_address_family_t af,
 				ip_sub_address_family_t safi,
 				ip_feature_location_t loc,
diff --git a/src/vnet/ip/ip4_inlines.h b/src/vnet/ip/ip4_inlines.h
index bdb82af0034..3075fbf42a1 100644
--- a/src/vnet/ip/ip4_inlines.h
+++ b/src/vnet/ip/ip4_inlines.h
@@ -89,6 +89,7 @@ ip4_compute_flow_hash (const ip4_header_t * ip,
   b ^= (flow_hash_config & IP_FLOW_HASH_PROTO) ? ip->protocol : 0;
   c = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ?
     (t1 << 16) | t2 : (t2 << 16) | t1;
+  a ^= ip_flow_hash_router_id;
 
   hash_v3_mix32 (a, b, c);
   hash_v3_finalize32 (a, b, c);
diff --git a/src/vnet/ip/ip6_inlines.h b/src/vnet/ip/ip6_inlines.h
index 8376377600a..2a4bb70573b 100644
--- a/src/vnet/ip/ip6_inlines.h
+++ b/src/vnet/ip/ip6_inlines.h
@@ -106,10 +106,13 @@ ip6_compute_flow_hash (const ip6_header_t * ip,
     }
 
   b ^= (flow_hash_config & IP_FLOW_HASH_PROTO) ? protocol : 0;
-  c = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ?
-    ((t1 << 16) | t2) : ((t2 << 16) | t1);
-  t1 = ip->ip_version_traffic_class_and_flow_label & IP6_PACKET_FL_MASK;
-  c ^= (flow_hash_config & IP_FLOW_HASH_FL) ? (t1 << 32) : 0;
+  c = ((flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ? ((t1 << 16) | t2) :
+							   ((t2 << 16) | t1));
+  t1 = ((u64) ip_flow_hash_router_id << 32);
+  t1 |=
+    ((flow_hash_config & IP_FLOW_HASH_FL) ? ip6_flow_label_network_order (ip) :
+					    0);
+  c ^= t1;
 
   hash_mix64 (a, b, c);
   return (u32) c;
diff --git a/src/vnet/ip/ip6_packet.h b/src/vnet/ip/ip6_packet.h
index 03aac1bd4d4..1be2ceae5a1 100644
--- a/src/vnet/ip/ip6_packet.h
+++ b/src/vnet/ip/ip6_packet.h
@@ -343,6 +343,13 @@ ip6_ecn_network_order (const ip6_header_t * ip6)
 	  & IP6_PACKET_ECN_MASK) >> 20;
 }
 
+static_always_inline u32
+ip6_flow_label_network_order (const ip6_header_t *ip6)
+{
+  return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label) &
+	  IP6_PACKET_FL_MASK);
+}
+
 static_always_inline void
 ip6_set_traffic_class_network_order (ip6_header_t * ip6, ip_dscp_t dscp)
 {
diff --git a/src/vnet/ip/ip_api.c b/src/vnet/ip/ip_api.c
index 37656f3232f..3bf404baadf 100644
--- a/src/vnet/ip/ip_api.c
+++ b/src/vnet/ip/ip_api.c
@@ -88,6 +88,7 @@
   _ (IP_PUNT_REDIRECT, ip_punt_redirect)                                      \
   _ (SET_IP_FLOW_HASH, set_ip_flow_hash)                                      \
   _ (SET_IP_FLOW_HASH_V2, set_ip_flow_hash_v2)                                \
+  _ (SET_IP_FLOW_HASH_ROUTER_ID, set_ip_flow_hash_router_id)                  \
   _ (IP_CONTAINER_PROXY_ADD_DEL, ip_container_proxy_add_del)                  \
   _ (IP_CONTAINER_PROXY_DUMP, ip_container_proxy_dump)                        \
   _ (IOAM_ENABLE, ioam_enable)                                                \
@@ -1046,6 +1047,18 @@ vl_api_set_ip_flow_hash_v2_t_handler (vl_api_set_ip_flow_hash_v2_t *mp)
   REPLY_MACRO (VL_API_SET_IP_FLOW_HASH_V2_REPLY);
 }
 
+static void
+vl_api_set_ip_flow_hash_router_id_t_handler (
+  vl_api_set_ip_flow_hash_router_id_t *mp)
+{
+  vl_api_set_ip_flow_hash_router_id_reply_t *rmp;
+  int rv = 0;
+
+  ip_flow_hash_router_id_set (ntohl (mp->router_id));
+
+  REPLY_MACRO (VL_API_SET_IP_FLOW_HASH_ROUTER_ID_REPLY);
+}
+
 void
 vl_mfib_signal_send_one (vl_api_registration_t * reg,
 			 u32 context, const mfib_signal_t * mfs)
diff --git a/src/vnet/ip/ip_flow_hash.h b/src/vnet/ip/ip_flow_hash.h
index 82e0efb0d08..bd37ef7307b 100644
--- a/src/vnet/ip/ip_flow_hash.h
+++ b/src/vnet/ip/ip_flow_hash.h
@@ -16,6 +16,8 @@
 #ifndef __IP_FLOW_HASH_H__
 #define __IP_FLOW_HASH_H__
 
+#include <vnet/ip/ip_types.h>
+
 /** Default: 5-tuple + flowlabel without the "reverse" bit */
 #define IP_FLOW_HASH_DEFAULT (0x9F)
 
@@ -48,6 +50,13 @@ typedef enum flow_hash_config_t_
 #undef _
 } flow_hash_config_t;
 
+/* Router ID mixed into the flow hash to prevent network polarisation */
+extern u32 ip_flow_hash_router_id;
+
+int ip_flow_hash_set (ip_address_family_t af, u32 table_id,
+		      flow_hash_config_t flow_hash_config);
+void ip_flow_hash_router_id_set (u32 router_id);
+
 #endif /* __IP_TYPES_H__ */
 
 /*
diff --git a/src/vnet/mpls/mpls_lookup.h b/src/vnet/mpls/mpls_lookup.h
index 5b88be17d8f..81c67cef8ee 100644
--- a/src/vnet/mpls/mpls_lookup.h
+++ b/src/vnet/mpls/mpls_lookup.h
@@ -53,6 +53,7 @@ mpls_compute_flow_hash (const mpls_unicast_header_t * hdr,
 
     ho_label = clib_net_to_host_u32(hdr->label_exp_s_ttl);
     hash = vnet_mpls_uc_get_label(ho_label);
+    hash ^= ip_flow_hash_router_id;
     next_label_is_entropy = 0;
 
     while (MPLS_EOS != vnet_mpls_uc_get_s(ho_label))