https://community.extremenetworks.com/t5/extremeswitching-exos-switch/ospf-log-error/m-p/43499#M10508 Hi Jasheer, <BR /> <BR /> I have seen this before and believe this translates to the OSPF neighbor changing state from FULL to EXSTART because of the receipt of a Database Description (DBD) packet from the neighbor with an unexpected sequence number.<BR /> <BR /> SeqNumberMismatch means that a DBD packet during OSPF neighborship negotiation has been received that either:<BR /> <BR /> <UL> <LI>has an unexpected DBD sequence number </LI><LI>unexpectedly has the Iimit bit set </LI><LI>has an Options field differing from the last Options field received in a Database Description packet. </LI></UL>This can be attributed to (Unidirectional) packet loss as a possible cause.<BR /> <BR /> So I would take a look at the port that the neighbour is connecting through and check for any packet loss.<BR /> <BR /> Thanks.<BR /> <BR /> Mon, 28 Sep 2015 15:12:00 GMT Anonymous 2015-09-28T15:12:00Z https://community.extremenetworks.com/t5/extremeswitching-exos-switch/ospf-log-error/m-p/43498#M10507 Hi,<BR /> My ospf link flopping continuously the switch log is showing below mentioned. kindly help as to solve this issue.. <BR /> <BR /> 09/28/2015 17:04:51.49 <OSPF.NEIGHBOR.PROCDDFAIL> Processing DD from neighbor 192.168.99.2 fails on NBR seqmismatch event,case else<BR /></OSPF.NEIGHBOR.PROCDDFAIL> Mon, 28 Sep 2015 14:39:00 GMT https://community.extremenetworks.com/t5/extremeswitching-exos-switch/ospf-log-error/m-p/43498#M10507 Mohammed_Jashee 2015-09-28T14:39:00Z https://community.extremenetworks.com/t5/extremeswitching-exos-switch/ospf-log-error/m-p/43499#M10508 Hi Jasheer, <BR /> <BR /> I have seen this before and believe this translates to the OSPF neighbor changing state from FULL to EXSTART because of the receipt of a Database Description (DBD) packet from the neighbor with an unexpected sequence number.<BR /> <BR /> SeqNumberMismatch means that a DBD packet during OSPF neighborship negotiation has been received that either:<BR /> <BR /> <UL> <LI>has an unexpected DBD sequence number </LI><LI>unexpectedly has the Iimit bit set </LI><LI>has an Options field differing from the last Options field received in a Database Description packet. </LI></UL>This can be attributed to (Unidirectional) packet loss as a possible cause.<BR /> <BR /> So I would take a look at the port that the neighbour is connecting through and check for any packet loss.<BR /> <BR /> Thanks.<BR /> <BR /> Mon, 28 Sep 2015 15:12:00 GMT https://community.extremenetworks.com/t5/extremeswitching-exos-switch/ospf-log-error/m-p/43499#M10508 Anonymous 2015-09-28T15:12:00Z