HP X09 Manual download pdf (Page 39)

XStream‐PKG‐E™EthernetRFModem–ProductManualv5.x00[2006.02.24]

5.1. Addressing

Each RF packet contains addressing information that is used to filter incoming RF data. Receiving

modems inspect the Hopping Channel (HP parameter), Vendor Identification Number (ID

parameter) and Destination Address (DT parameter) contained in each RF packet. Data that does

not pass through all three network security layers is discarded.

Figure5‐01. FiltrationlayerscontainedintheRFpacketheader

5.1.1. Address Recognition

Transmissions can be addressed to a specific modem or group of modems using the DT

(Destination Address) and MK (Address Mask) parameters. The transmitting modem dictates

whether the packet is intended for a specific modem (local address) or multiple modems (global

address) by comparing the packet’s DT parameter to its own MK parameter.

Figure5‐02. LocalPacketsvs.GlobalPackets(TransmittingModem)

TX_DT=TransmitterDestinationAddress

TX_MK=TransmitterAddressMask

Note:WhenTX_DT=0xFFFF(default),RFpacketsareglobalandare

receivedbyallmodemswithinrange.(ReceiversdonotsendACKs.)

A receiving modem will only accept a packet if a packet is addressed to it (either as a global or

local packet). The RX modem makes this determination by inspecting the destination address of

the RF packet and comparing it to its own address and mask. The Destination Address of the TX

modem is logically “ANDed” with the Address Mask of the RX modem.

Figure5‐03. AddressRecognition(ReceivingModem)

TX_DT=TransmitterDestinationAddress

RX_DT=ReceiverDestinationAddress

RX_MY=ReceiverSourceAddress

NOTE: For more information regarding addressing and masks, refer to Application Note ‘XST-

AN004b’. (Located on the MaxStream CD and on the web: www.maxstream.net)

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HP X09 Manual Page 39