How to modify the filter of H225-RAS ports

This page describes the way to configure the protocol filter with the following features:

  • setting the UDP  ports

Connecting the unit and setting the test conditions:

The connections of Clarinet-Book USB units and the settings of test conditions for a basic H323 communication using the H245 procedures  are detailed in the following page:

Setting the test conditions for H323 filter

The protocol filter file Lan_auto_h323.acf   (created  with the Wizard from the Template list) specifies the stack of protocol. As the IP protocols are automatically detected by the protocol value, the stack defined in the "Protocol specification"  has the layers D3 to D7 set to "Automatic"

However the ports used by H225-RAS, H225-Signalling and RTCP/RTP may change.

The ports values are specified in the panel:

 Protocol specification èParameters è (DataLink)-Ports 

This panel shows 3 ranges of ports which are used sequentially (step1, then step2, then step3) to decode the protocols according to the port values:

  • 1- Port numbers (dst or src): each values of the ports corresponds to the "well-known" values used by the protocol stack defined in Protocol(n), Protocol(n+1), Protocol(n+2), Protocol(n+3).
  • 2- Attempt to decode: the values which have not been decoded by the step1  correspond generally to regular protocols:
    • UDP ports : attend to decode RTP/RTCP protocols
    • TCP ports: attend to decode TPKT protocol and then:
      • H225 signalling over T123-TPKT
      • X224 over T123-TPKT
  • 3- Default ports: the values which have not been decoded by the step1 and step2 could correspond  to default protocols:
    • UDP ports : attempt to decode H225-RAS protocol
    • TCP ports: attempt to decode H245 protocol 
    • .....

 Example: Port number=1719 correspond to UDP +  H225-RAS. 

But if some other UDP ports are used for carrying IP traffic, the Default port specify for UDP will cause an attempt to decode H225-RAS over these ports. An error in the ASN1 fields will be generated.

The Default port value for UDP H225-RAS should be removed to avoid these attempts of  decoding over wrong ports.

 

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updated:  27-Feb-04