Configuring Port-Based Traffic Control 695What is Link Local Protocol Filtering?The Link Local Protocol Filtering (LLPF) feature can help troubleshootnetwork problems that occur when a network includes proprietary protocolsrunning on standards-based switches. LLPF allows a PowerConnectM6220/M6348/M8024/M8024-k switch to filter out various Cisco ®proprietary protocol data units (PDUs) and/or ISDP if problems occur withthese protocols running on standards-based switches. If certain protocolPDUs cause unexpected results, LLPF can be enabled to prevent thoseprotocol PDUs from being processed by the switch.The LLPF feature can be configured per-port to block any combination (orall) of the following PDUs:• Industry Standard Discovery Protocol (ISDP)• VLAN Trunking Protocol (VTP)• Dynamic Trunking Protocol (DTP)• UniDirectional Link Detection (UDLD)• Port Aggregation Protocol (PAgP)• Shared Spanning Tree Protocol (SSTP)Access Control Lists (ACLs) and LLPF can exist on the same interface.However, the ACL rules override the LLPF rules when there is a conflict.Similarly, DiffServ and LLPF can both be enabled on an interface, butDiffServ rules override LLPF rules when there is a conflict.If Industry Standard Discovery Protocol (ISDP) is enabled on an interface,and the LLPF feature on an interface is enabled and configured to drop ISDPPDUs, the ISDP configuration overrides the LLPF configuration, and theISDP PDUs are allowed on the interface.
