bgpd: re-eval use-l3nhg when a remote ES is [de]activated in a VRF

There are two changes in this commit -

1. Maintain a list of global MAC-IP routes per-ES. This list is maintained
for quick processing on the following events -
a. When the first VTEP/PE becomes active in the ES-VRF, the L3 NHG is
activated and the route can be sent to zebra.
b. When there are no active PEs in the ES-VRF the L3 NHG is
de-activated and -
- If the ES is present in the VRF -
The route is not installed in zebra as there are no active PEs for
the ES-VRF
- If the ES is not present in the VRF -
The route is installed with a flat multi-path list i.e. without L3NHG.
This is to handle the case where there are no locally attached L2VNIs
on the ES (for that tenant VRF).

2. Reinstall VRF route when an ES is installed or uninstalled in a
tenant VRF (the global MAC-IP list in #1 is used for this purpose also).
If an ES is present in the VRF we use L3NHG to enable fast-failover of
routed traffic.

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

1 files changed, 64 insertions, 68 deletions

diff --git a/bgpd/bgp_evpn.c b/bgpd/bgp_evpn.c
index a4d4dbc20..26e880c0d 100644
--- a/bgpd/bgp_evpn.c
+++ b/bgpd/bgp_evpn.c
@@ -1597,8 +1597,8 @@ static int update_evpn_route_entry(struct bgp *bgp, struct bgpevpn *vpn,
 		}
 	}
 
-	/* MAC-IP routes in the VNI route table are linked to the
-	 * destination ES
+	/* local MAC-IP routes in the VNI table are linked to
+	 * the destination ES
 	 */
 	if (route_change && vpn_rt
 	    && (evp->prefix.route_type == BGP_EVPN_MAC_IP_ROUTE))
@@ -2378,6 +2378,8 @@ static int install_evpn_route_entry_in_vrf(struct bgp *bgp_vrf,
 	afi_t afi = 0;
 	safi_t safi = 0;
 	bool new_pi = false;
+	bool use_l3nhg = false;
+	bool is_l3nhg_active = false;
 
 	memset(pp, 0, sizeof(struct prefix));
 	ip_prefix_from_evpn_prefix(evp, pp);
@@ -2413,6 +2415,13 @@ static int install_evpn_route_entry_in_vrf(struct bgp *bgp_vrf,
 	else
 		attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_NEXT_HOP);
 
+	bgp_evpn_es_vrf_use_nhg(bgp_vrf, &parent_pi->attr->esi, &use_l3nhg,
+				&is_l3nhg_active, NULL);
+	if (use_l3nhg)
+		attr.es_flags |= ATTR_ES_L3_NHG_USE;
+	if (is_l3nhg_active)
+		attr.es_flags |= ATTR_ES_L3_NHG_ACTIVE;
+
 	/* Check if route entry is already present. */
 	for (pi = bgp_dest_get_bgp_path_info(dest); pi; pi = pi->next)
 		if (pi->extra
@@ -2532,11 +2541,6 @@ static int install_evpn_route_entry(struct bgp *bgp, struct bgpevpn *vpn,
 		pi->uptime = bgp_clock();
 	}
 
-	/* MAC-IP routes in the VNI table are linked to the destination ES */
-	if (p->prefix.route_type == BGP_EVPN_MAC_IP_ROUTE)
-		bgp_evpn_path_es_link(pi, vpn->vni,
-				      bgp_evpn_attr_get_esi(pi->attr));
-
 	/* Perform route selection and update zebra, if required. */
 	ret = evpn_route_select_install(bgp, vpn, dest);
 
@@ -2857,7 +2861,6 @@ bgp_evpn_skip_vrf_import_of_local_es(struct bgp *bgp_vrf,
 				     struct bgp_path_info *pi, int install)
 {
 	esi_t *esi;
-	struct in_addr nh;
 
 	if (evp->prefix.route_type == BGP_EVPN_MAC_IP_ROUTE) {
 		esi = bgp_evpn_attr_get_esi(pi->attr);
@@ -2875,30 +2878,52 @@ bgp_evpn_skip_vrf_import_of_local_es(struct bgp *bgp_vrf,
 			}
 			return true;
 		}
+	}
+	return false;
+}
 
-		/* Don't import routes with ES as destination if L3NHG is in
-		 * use and the nexthop has not been advertised via the EAD-ES
-		 */
-		if (pi->attr)
-			nh = pi->attr->nexthop;
+/*
+ * Install or uninstall a mac-ip route in the provided vrf if
+ * there is a rt match
+ */
+int bgp_evpn_route_entry_install_if_vrf_match(struct bgp *bgp_vrf,
+					      struct bgp_path_info *pi,
+					      int install)
+{
+	int ret = 0;
+	const struct prefix_evpn *evp =
+		(const struct prefix_evpn *)bgp_dest_get_prefix(pi->net);
+
+	/* Consider "valid" remote routes applicable for
+	 * this VRF.
+	 */
+	if (!(CHECK_FLAG(pi->flags, BGP_PATH_VALID)
+	      && pi->type == ZEBRA_ROUTE_BGP
+	      && pi->sub_type == BGP_ROUTE_NORMAL))
+		return 0;
+
+	/* don't import hosts that are locally attached */
+	if (bgp_evpn_skip_vrf_import_of_local_es(bgp_vrf, evp, pi, install))
+		return 0;
+
+	if (is_route_matching_for_vrf(bgp_vrf, pi)) {
+		if (bgp_evpn_route_rmac_self_check(bgp_vrf, evp, pi))
+			return 0;
+
+		if (install)
+			ret = install_evpn_route_entry_in_vrf(bgp_vrf, evp, pi);
 		else
-			nh.s_addr = INADDR_ANY;
-		if (install && !bgp_evpn_es_vrf_import_ok(bgp_vrf, esi, nh)) {
-			if (BGP_DEBUG(evpn_mh, EVPN_MH_RT)) {
-				char esi_buf[ESI_STR_LEN];
+			ret = uninstall_evpn_route_entry_in_vrf(bgp_vrf, evp,
+								pi);
 
-				zlog_debug(
-					"vrf %s %s of evpn prefix %pFX skipped, nh %pI4 inactive in es %s",
-					bgp_vrf->name,
-					install ? "import" : "unimport", evp,
-					&nh,
-					esi_to_str(esi, esi_buf,
-						   sizeof(esi_buf)));
-			}
-			return true;
-		}
+		if (ret)
+			flog_err(EC_BGP_EVPN_FAIL,
+				 "Failed to %s EVPN %pFX route in VRF %s",
+				 install ? "install" : "uninstall", evp,
+				 vrf_id_to_name(bgp_vrf->vrf_id));
 	}
-	return false;
+
+	return ret;
 }
 
 /*
@@ -2950,46 +2975,10 @@ static int install_uninstall_routes_for_vrf(struct bgp *bgp_vrf, int install)
 
 			for (pi = bgp_dest_get_bgp_path_info(dest); pi;
 			     pi = pi->next) {
-				/* Consider "valid" remote routes applicable for
-				 * this VRF.
-				 */
-				if (!(CHECK_FLAG(pi->flags, BGP_PATH_VALID)
-				      && pi->type == ZEBRA_ROUTE_BGP
-				      && pi->sub_type == BGP_ROUTE_NORMAL))
-					continue;
-
-				/* don't import hosts that are locally attached
-				 */
-				if (bgp_evpn_skip_vrf_import_of_local_es(
-					    bgp_vrf, evp, pi, install))
-					continue;
-
-				if (is_route_matching_for_vrf(bgp_vrf, pi)) {
-					if (bgp_evpn_route_rmac_self_check(
-								bgp_vrf, evp, pi))
-						continue;
-
-					if (install)
-						ret = install_evpn_route_entry_in_vrf(
-							bgp_vrf, evp, pi);
-					else
-						ret = uninstall_evpn_route_entry_in_vrf(
-							bgp_vrf, evp, pi);
-
-					if (ret) {
-						flog_err(
-							EC_BGP_EVPN_FAIL,
-							"Failed to %s EVPN %pFX route in VRF %s",
-							install ? "install"
-								: "uninstall",
-							evp,
-							vrf_id_to_name(
-								bgp_vrf->vrf_id));
-						bgp_dest_unlock_node(rd_dest);
-						bgp_dest_unlock_node(dest);
-						return ret;
-					}
-				}
+				ret = bgp_evpn_route_entry_install_if_vrf_match(
+					bgp_vrf, pi, install);
+				if (ret)
+					return ret;
 			}
 		}
 	}
@@ -3293,6 +3282,13 @@ static int bgp_evpn_install_uninstall_table(struct bgp *bgp, afi_t afi,
 		if (sub_type != ECOMMUNITY_ROUTE_TARGET)
 			continue;
 
+		/* non-local MAC-IP routes in the global route table are linked
+		 * to the destination ES
+		 */
+		if (evp->prefix.route_type == BGP_EVPN_MAC_IP_ROUTE)
+			bgp_evpn_path_es_link(pi, 0,
+					      bgp_evpn_attr_get_esi(pi->attr));
+
 		/*
 		 * macip routes (type-2) are imported into VNI and VRF tables.
 		 * IMET route is imported into VNI table.