the customer reports that the ospf status stucked in the exstart after replace one Cisco switch to Huawei S6720. the ospf is implemented between Huawei s6720 and Cisco 3650 switch, the two switch connect to each other directly.
topology as below:
1. check the connection interface MTU, found no such configuration.
2. check the ospf error packets, no error packets found.
3. check if there are any traffic policys which block the ospf DBD packets, because of the DBD packets are sent with unicast, so it may be blocked by the traffic policy. after checking the configuration, no such policy found.
4. confirmed with the customer, we learned that S6720 replaced another Cisco switch, and they configure the S6720 with the same configuration as the Cisco switch.
5. check the Cisco 3650, found that there are ip bindings which restrict the devices with the specific binding entries can access the switch.
6. modify the ip binding, the OSPF turns to up.
the ip bindings ignore the DBD packets which sent by the S6720, because the ip address and mac address match none binding entries.
modify the ip binding entry on the Cisco 3650. modify the mac address which belongs to the previous 3650 switch in the ip binding entry into the S6720's mac address