The message code to be checked against the packet. If the packet matches with the message code, then the packet will be dropped / allowed based on the action set in issL3FilterAction. The default value is 255. It means that message code is not configured and need not be checked. Generally the value zero will be given as default. But here, zero can be an ICMP Code value. Hence 255 is given as the default value. Some ICMP message codes are : networkUnreachable(0), hostUnreachable(1), protocolUnreachable(2), portUnreachable(3), fragmentNeed(4), sourceRouteFail(5), destNetworkUnknown(6), destHostUnknown(7), srcHostIsolated(8), destNetworkAdminProhibited(9), destHostAdminProhibited(10), networkUnreachableTOS(11), hostUnreachableTOS(12), noICMPCode(255) This object is deprecated and the corresponding functionality is met with issL3Filter objects in fsissext.mib.