1. From the log, we can see S5700 receives LLDP from Cisco. Using below debugging command to check the LLDP packet
debugging lldp packet interface GigabitEthernet 0/0/1
debugging lldp event interface GigabitEthernet 0/0/1
2. We found below error in debugging.
Nov 12 2013 13:51:00.430.2-05:13 S5328C-EI_96 DBGCENTER/7/DEBUG:pkt check fail for sys cap not same in LLDP_IsPacketValid.
After analyzed the LLDP packets from Cisco, we found packets from Cisco indicate they support Bridge Capabilities in Capabilities TLV. However, Cisco enable two capabilities Bridge and Router
Regarding standard LLDP protocol, this kind of packets should be dropped.
3. LLDP packets from Cisco is no standard. Let customer disable LLDP on Cisco. And it is solved.