zebra: Do not pathcount EVPN A-D prefixes

With EVPN MH zebra is treating route adds as upsert operations. However pathcounting these upserts would lead to a never really decreasing counter. Route deletions for EVPN MH should fully remove the dummy prefix from the next-hop. Disabling increasing of the pathcount yields the same behaviour for this type of route Signed-off-by: Christopher Dziomba <[email protected]>
FRRouting · Feb 15, 2025 · de9f8c7 · de9f8c7
1 parent f9ab5d8
commit de9f8c7
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/zebra/zebra_evpn_mh.c b/zebra/zebra_evpn_mh.c
@@ -3795,7 +3795,7 @@ void zebra_evpn_proc_remote_nh(ZAPI_HANDLER_ARGS)
 	memset(&dummy_prefix, 0, sizeof(dummy_prefix));
 	dummy_prefix.family = AF_EVPN;
 	dummy_prefix.prefixlen = (sizeof(struct evpn_addr) * 8);
-	dummy_prefix.prefix.route_type = 1; /* XXX - fixup to type-1 def */
+	dummy_prefix.prefix.route_type = BGP_EVPN_AD_ROUTE; /* XXX - fixup to type-1 def */
 	dummy_prefix.prefix.ead_addr.ip.ipa_type = nh.ipa_type;
 
 	if (hdr->command == ZEBRA_EVPN_REMOTE_NH_ADD) {

diff --git a/zebra/zebra_vxlan.c b/zebra/zebra_vxlan.c
@@ -1147,6 +1147,15 @@ static void rb_find_or_add_host(struct host_rb_tree_entry *hrbe,
 
 	hle = RB_FIND(host_rb_tree_entry, hrbe, &lookup);
 	if (hle) {
+		/* never pathcount evpn A-D / MH routes because zebra is not aware
+		 * of specific paths. ADD operations are considered to be upsert
+		 * leading to path count increasing without ever decreasing. A single
+		 * DEL operation should fully remove the prefix from the next-hop.
+		 */
+		if (host->family == AF_EVPN
+			&& ((const struct prefix_evpn *)&host)->prefix.route_type == BGP_EVPN_AD_ROUTE)
+			return;
+
 		hle->pathcnt++;
 		return;
 	}