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 70da39ee8b43335f217f36586b3abe4764c20869..ef9c313c9aece3b1e289d6d0fece1cf48f666557 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -1064,7 +1064,32 @@ 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)) {
@@ -1094,34 +1119,6 @@ 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 6a46128d72d2a3800dac8723e9cae3ee77ae3e2e..f2005c18dd63269c4000eed165c7301e8bfd25d6 100644 (file)
--- a/doc/user/bgp.rst
+++ b/doc/user/bgp.rst
@@ -160,16 +160,16 @@ 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.