zebra: Score weighted values of ecmp to a number between 1-255

Currently underlying asics get into a bit of trouble when the nexthop weight passed down varies wildly between the different numbers. Let's normalize the weight values between 1 and 255 Signed-off-by: Donald Sharp <[email protected]>
donaldsharp · Sep 28, 2023 · cb5c1c9 · cb5c1c9
1 parent 8640fc9
commit cb5c1c9
Showing 1 changed file with 42 additions and 0 deletions.
diff --git a/zebra/zapi_msg.c b/zebra/zapi_msg.c
@@ -1857,6 +1857,8 @@ static int zapi_nhg_decode(struct stream *s, int cmd, struct zapi_nhg *api_nhg)
 {
 	uint16_t i;
 	struct zapi_nexthop *znh;
+	bool same_weight = true;
+	uint64_t max_weight = 0;
 
 	STREAM_GETW(s, api_nhg->proto);
 	STREAM_GETL(s, api_nhg->id);
@@ -1888,8 +1890,29 @@ static int zapi_nhg_decode(struct stream *s, int cmd, struct zapi_nhg *api_nhg)
 				  "%s: Nexthop creation failed", __func__);
 			return -1;
 		}
+
+		if (max_weight < znh->weight) {
+			if (i != 0)
+				same_weight = false;
+
+			max_weight = znh->weight;
+		}
+	}
+
+	if (!same_weight) {
+		for (i = 0; i < api_nhg->nexthop_num; i++) {
+			uint64_t tmp;
+
+			znh = &((api_nhg->nexthops)[i]);
+
+			tmp = (uint64_t)znh->weight * 255;
+			znh->weight = MAX(1, ((uint32_t)(tmp/max_weight)));
+		}
 	}
 
+	same_weight = true;
+	max_weight = 0;
+
 	/* Backup Nexthops */
 	STREAM_GETW(s, api_nhg->backup_nexthop_num);
 
@@ -1905,8 +1928,27 @@ static int zapi_nhg_decode(struct stream *s, int cmd, struct zapi_nhg *api_nhg)
 				  __func__);
 			return -1;
 		}
+
+                if (max_weight < znh->weight) {
+                        if (i != 0)
+                                same_weight = false;
+
+                        max_weight = znh->weight;
+                }
+
 	}
 
+        if (!same_weight) {
+                for (i = 0; i < api_nhg->nexthop_num; i++) {
+                        uint64_t tmp;
+
+                        znh = &((api_nhg->backup_nexthops)[i]);
+
+                        tmp = (uint64_t)znh->weight * 255;
+                        znh->weight = MAX(1, ((uint32_t)(tmp/max_weight)));
+                }
+        }
+
 done:
 	return 0;