pimd: Process no-forward BSM packet

Topology Used:
=============
Cisco---FRR4----FRR2

Initially PIM nbr is down between FRR4----FRR2 from FRR2 side
Cisco is sending BSR packet to FRR4.

Problem Statement:
=================
No shutdown the PIM neighbor on FRR2 towards FRR4.
FRR2, receives BSR packet immediately as the new neighbor
comes up. This BSR packet is having no-forward bit set.
FRR2 is not able to process the BSR packet, and drop the
BSR packet.

Root Cause:
==========
When PIMD comes up, we start BSM timer for 60 seconds.
Here, the value accept_nofwd_bsm is setting to false.

FRR2, when receives no-forward BSR packet, it is getting
accept_nofwd_bsm value as false.

So, it drops, the no-forward BSM packet.

Fix:
===
Set accept_nofwd_bsm as false after first BSM packet received.

Signed-off-by: Sarita Patra <saritap@vmware.com>
(cherry picked from commit 8b462d557905200d98c7a8965b3d223637c3c5dd)

diff --git a/pimd/pim_bsm.c b/pimd/pim_bsm.c
index 1f7dd2f3f92be2e13c46d7ae75c696eca9af98e9..9942886b7786f4e8961d40c06b5810a0ecfc8da4 100644 (file)
--- a/pimd/pim_bsm.c
+++ b/pimd/pim_bsm.c
@@ -170,7 +170,6 @@ static void pim_on_bs_timer(struct thread *t)
 
        pim_nht_bsr_del(scope->pim, scope->current_bsr);
        /* Reset scope zone data */
-       scope->accept_nofwd_bsm = false;
        scope->state = ACCEPT_ANY;
        scope->current_bsr = PIMADDR_ANY;
        scope->current_bsr_prio = 0;
@@ -1378,6 +1377,10 @@ int pim_bsm_process(struct interface *ifp, pim_sgaddr *sg, uint8_t *buf,
                }
        }
 
+       /* BSM packet is seen, so resetting accept_nofwd_bsm to false */
+       if (pim->global_scope.accept_nofwd_bsm)
+               pim->global_scope.accept_nofwd_bsm = false;
+
        if (!pim_addr_cmp(sg->grp, qpim_all_pim_routers_addr)) {
                /* Multicast BSMs are only accepted if source interface & IP
                 * match RPF towards the BSR's IP address, or they have