Merge pull request #4874 from manuhalo/fix_isis_mtu

[mirror_frr.git] / isisd / isis_northbound.c

diff --git a/isisd/isis_northbound.c b/isisd/isis_northbound.c
index 25c7058f3fb755888d003d7a09091ff4d6994e42..c1b630eb2db59a6396c360a1442ec0907460dc09 100644 (file)
--- a/isisd/isis_northbound.c
+++ b/isisd/isis_northbound.c
@@ -1524,29 +1524,64 @@ static int lib_interface_isis_create(enum nb_event event,
        struct interface *ifp;
        struct isis_circuit *circuit;
        const char *area_tag = yang_dnode_get_string(dnode, "./area-tag");
+       uint32_t min_mtu, actual_mtu;
 
-       if (event != NB_EV_APPLY)
-               return NB_OK;
+       switch (event) {
+       case NB_EV_PREPARE:
+       case NB_EV_ABORT:
+               break;
+       case NB_EV_VALIDATE:
+               /* check if interface mtu is sufficient. If the area has not
+                * been created yet, assume default MTU for the area
+                */
+               ifp = nb_running_get_entry(dnode, NULL, true);
+               /* zebra might not know yet about the MTU - nothing we can do */
+               if (ifp->mtu == 0)
+                       break;
+               actual_mtu =
+                       if_is_broadcast(ifp) ? ifp->mtu - LLC_LEN : ifp->mtu;
+               area = isis_area_lookup(area_tag);
+               if (area)
+                       min_mtu = area->lsp_mtu;
+               else
+#ifndef FABRICD
+                       min_mtu = yang_get_default_uint16(
+                               "/frr-isisd:isis/instance/lsp/mtu");
+#else
+                       min_mtu = DEFAULT_LSP_MTU;
+#endif /* ifndef FABRICD */
+               if (actual_mtu < min_mtu) {
+                       flog_warn(EC_LIB_NB_CB_CONFIG_VALIDATE,
+                                 "Interface %s has MTU %" PRIu32
+                                 ", minimum MTU for the area is %" PRIu32 "",
+                                 ifp->name, actual_mtu, min_mtu);
+                       return NB_ERR_VALIDATION;
+               }
+               break;
+       case NB_EV_APPLY:
+               area = isis_area_lookup(area_tag);
+               /* The area should have already be created. We are
+                * setting the priority of the global isis area creation
+                * slightly lower, so it should be executed first, but I
+                * cannot rely on that so here I have to check.
+                */
+               if (!area) {
+                       flog_err(
+                               EC_LIB_NB_CB_CONFIG_APPLY,
+                               "%s: attempt to create circuit for area %s before the area has been created",
+                               __func__, area_tag);
+                       abort();
+               }
 
-       area = isis_area_lookup(area_tag);
-       /* The area should have already be created. We are
-        * setting the priority of the global isis area creation
-        * slightly lower, so it should be executed first, but I
-        * cannot rely on that so here I have to check.
-        */
-       if (!area) {
-               flog_err(
-                       EC_LIB_NB_CB_CONFIG_APPLY,
-                       "%s: attempt to create circuit for area %s before the area has been created",
-                       __func__, area_tag);
-               abort();
+               ifp = nb_running_get_entry(dnode, NULL, true);
+               circuit = isis_circuit_create(area, ifp);
+               assert(circuit
+                      && (circuit->state == C_STATE_CONF
+                          || circuit->state == C_STATE_UP));
+               nb_running_set_entry(dnode, circuit);
+               break;
        }
 
-       ifp = nb_running_get_entry(dnode, NULL, true);
-       circuit = isis_circuit_create(area, ifp);
-       assert(circuit->state == C_STATE_CONF || circuit->state == C_STATE_UP);
-       nb_running_set_entry(dnode, circuit);
-
        return NB_OK;
 }