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 15e771dffb1af883cb8864a9699c5446962dcd65..e894db76519868174b0dc1d8b7331da5b0fd42f8 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -966,7 +966,32 @@ 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)) {
@@ -996,34 +1021,6 @@ 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 eaba92af8dff9c57136355374cc67721a4a8986f..102ce845c837e1d8410a34f89e83a73244a0edbe 100644 (file)
--- a/doc/user/bgp.rst
+++ b/doc/user/bgp.rst
@@ -154,16 +154,16 @@ 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.