bgpd: compare aigp after local route check in bgp_path_info_cmp()

For consistency between RIB and BGP, the aigp comparison should
be made after the local route check in bgp bestpath selection.

Signed-off-by: Enke Chen <enchen@paloaltonetworks.com>

diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 6dc19a62565a182e825003a49d2147b9795917a3..4f1afac5d53d94b0628a03363c5a9759c5be3449 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -953,7 +953,32 @@ int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                }
        }
 
-       /* Tie-breaker - AIGP (Metric TLV) attribute */
+       /* 3. Local route check. We prefer:
+        *  - BGP_ROUTE_STATIC
+        *  - BGP_ROUTE_AGGREGATE
+        *  - BGP_ROUTE_REDISTRIBUTE
+        */
+       new_origin = !(new->sub_type == BGP_ROUTE_NORMAL || new->sub_type == BGP_ROUTE_IMPORTED);
+       exist_origin = !(exist->sub_type == BGP_ROUTE_NORMAL ||
+                        exist->sub_type == BGP_ROUTE_IMPORTED);
+
+       if (new_origin && !exist_origin) {
+               *reason = bgp_path_selection_local_route;
+               if (debug)
+                       zlog_debug("%s: %s wins over %s due to preferred BGP_ROUTE type", pfx_buf,
+                                  new_buf, exist_buf);
+               return 1;
+       }
+
+       if (!new_origin && exist_origin) {
+               *reason = bgp_path_selection_local_route;
+               if (debug)
+                       zlog_debug("%s: %s loses to %s due to preferred BGP_ROUTE type", pfx_buf,
+                                  new_buf, exist_buf);
+               return 0;
+       }
+
+       /* 3.5. Tie-breaker - AIGP (Metric TLV) attribute */
        if (CHECK_FLAG(newattr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP)) &&
            CHECK_FLAG(existattr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP)) &&
            CHECK_FLAG(bgp->flags, BGP_FLAG_COMPARE_AIGP)) {
@@ -983,34 +1008,6 @@ int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                }
        }
 
-       /* 3. Local route check. We prefer:
-        *  - BGP_ROUTE_STATIC
-        *  - BGP_ROUTE_AGGREGATE
-        *  - BGP_ROUTE_REDISTRIBUTE
-        */
-       new_origin = !(new->sub_type == BGP_ROUTE_NORMAL ||
-                      new->sub_type == BGP_ROUTE_IMPORTED);
-       exist_origin = !(exist->sub_type == BGP_ROUTE_NORMAL ||
-                        exist->sub_type == BGP_ROUTE_IMPORTED);
-
-       if (new_origin && !exist_origin) {
-               *reason = bgp_path_selection_local_route;
-               if (debug)
-                       zlog_debug(
-                               "%s: %s wins over %s due to preferred BGP_ROUTE type",
-                               pfx_buf, new_buf, exist_buf);
-               return 1;
-       }
-
-       if (!new_origin && exist_origin) {
-               *reason = bgp_path_selection_local_route;
-               if (debug)
-                       zlog_debug(
-                               "%s: %s loses to %s due to preferred BGP_ROUTE type",
-                               pfx_buf, new_buf, exist_buf);
-               return 0;
-       }
-
        /* Here if these are imported routes then get ultimate pi for
         * path compare.
         */

diff --git a/doc/user/bgp.rst b/doc/user/bgp.rst
index 35004db2fba8a95cd4610aa56046a038b752c286..46653595f42e9a6e5d7ae4725e71eb80676251d9 100644 (file)
--- a/doc/user/bgp.rst
+++ b/doc/user/bgp.rst
@@ -157,16 +157,16 @@ bottom until one of the factors can be used.
 
    Prefer higher local preference routes to lower.
 
+3. **Local route check**
+
+   Prefer local routes (statics, aggregates, redistributed) to received routes.
+
    If ``bgp bestpath aigp`` is enabled, and both paths that are compared have
    AIGP attribute, BGP uses AIGP tie-breaking unless both of the paths have the
    AIGP metric attribute. This means that the AIGP attribute is not evaluated
    during the best path selection process between two paths when one path does
    not have the AIGP attribute.
 
-3. **Local route check**
-
-   Prefer local routes (statics, aggregates, redistributed) to received routes.
-
 4. **AS path length check**
 
    Prefer shortest hop-count AS_PATHs.