Administrator Guide

852 Port-Based Traffic Control
occur with these protocols running on standards-based switches. If certain
protocol PDUs cause unexpected results, LLPF can be enabled to prevent
those PDUs from being processed by the switch.
The LLPF feature can be configured per-port to block any combination (or
all) 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, but
DiffServ 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 ISDP
PDUs, the ISDP configuration overrides the LLPF configuration, and the
ISDP PDUs are allowed on the interface.