OLT transparent OSPF multicast packets(SCUN) neighbor flapping

Issue Description
Protect group using dual parenting. When OLT1 down and OLT2 cannot recover service ONT immediately Alarm Information
Handling Process

  1. Customer confirm connect the 2 routers in vendor J switch directly, the OSPF no any issue.
  2. 2 routers connect OLT and ONT network, if change the OSPF port type to NBMA network no issue, if a change to broadcast the neighbor flapping.
  3. OSPF neighbor keeps by the hello message, in NBMA type network, hello packets send by unicast, broadcast network type hello packets sent to multicast group .suspect the multicast packets ware suppressed.
  4. Try to configure the unknown multicast packets transparent in service port and ONT , the problem still not solved.
  5. In the ONT mirror LAN port and pon port, confirmed the hello packets send by 10.10.10.1 normal, but packets from 10.10.10.0 through OLT send to multicast group 224.0.0.5 too less.
  6. Try to change the multicast suppress value to a big value to allow more multicast packets through OLT uplink port at same time, until change to value 12 , monitor in the ONT eth port capture confirm the packets from 10.10.10.0 send to 224.0.0.0.5 normal

Root Cause
the SCUN board hardware limit, cannot recognize the routing protocol multicast packets.
Solution

  1. configure the multicast-unknown policy for the ONT service  port to allow  transparent unknown multicast packets

Command: multicast-unknown policy service-port 9608 transparent

  1. Enable  the ONT transparent packets (configured it in the ont SRV profile )

Command: transparent enable

  1. Adjust the multicast suppress value to a big value or remove the multicast suppress from the uplink port.

Command: traffic-suppress 0 multicast value 12
4. Remove the uplink port multicast suppress command :
Command: undo traffic-suppress 0 multicast
Suggestions
SCUN board hardware difference with the SCUB/SCUL, cannot recognize the routing protocol multicast packets by inner ACL, cannot solve it through upgrade version also. If in the SCUN type OLT transparent dynamic routing protocol, except the service port allow transparent unknown multicast and ONT allow transparent, the OLT uplink port multicast packets suppress need to be adjusted also.