PDF user manual for CopperEdge 150

,QWHUIDFH)LOWHUVWhen you configure a DSL interface with the IP netmodel, theCE150 allows all inbound messages to pass through withoutregard to IP address. Normally, the subscriber equipment processesonly message packets that contain its IP address and ignorespackets with a different address. Occasionally, datashould not even reach a subscriber’s equipment. A business,for example, would want to ensure that its message traffic is notaccessible to its competition.,3)LOWHULQJIP filtering allows links to selectively pass or discard inbound IPpackets based on parameters set by the operator. In general, filteringapplies only to packets that are full-IP routed. The oneexception is for packets that are policy routed to the IP addressof the same DSL interface through which they entered theCE150 (such as a Ping from a device on a LAN at the customerpremise to the IP address of its own associated CE150 DSL interface).Otherwise, policy-routed packets are not filtered.Filtering cannot be done on interfaces with a networking modelother than IP or HDIA. Also, filtering works only on inboundpackets, before they reach the IP stack. Note, however, thatpackets may be inbound from either a WAN interface or from aDSL interface, provided they are destined for an IP address thatterminates in the CE150 itself. The following flow chart showsthe general flow of filtered packets in the CE150.Packetsfrom CPEPolicyAddressedto this sameDSL port?NTo WAN VCPacketsfrom WANVCDSLInterfaceFwd Mode?FullIPYInterfaceFilterPassedPacketsInterfaceFilterWAN VCInterfaceDoes packetterminatein CE?NForward to next hopTo WAN VCYCESystemFilterCEIP Applications(SNMP, Telnet, etc.)IP Filtering and Packet Flow in the CopperEdge DSLAM&KDSWHU$GYDQFHG&RQILJXUDWLRQ