13.6.5  
Fax over IP with HG 1500 
 
Fax over IP guarantees the compatibility of traditional analog fax devices in IP telephony networks. The following scenarios must be taken into account when using the real-time communication system HiPath 3000 with the HG 1500 board.
For Fax over IP the IP network must meet certain quality criteria that are determined in the network analysis as otherwise interruptions can occur in the fax transmission. Otherwise the connection and marketing of separate trunk lines should be provided for each node.
In general, an IP trunking network is when two or more HiPath 3000 systems are networked to each other over the integrated HG 1500 board. The HG 1500 board supports two functions for transferring the fax information.
 •   Fax over G.711 ("IP/IP e2e payload via enterprise proxy" connection)
    The advantage of E.711 is that (unlike T.38) high speed faxes (in other words faxes with a transmission rate > 14400 bps) can also use this higher transmission rate on a good network, while high speed faxes must be slowed down to a speed of 14400 bps when T.38 is used.
 •   T.38
    T.38 is an ITU standard that describes how two fax machines communicate over IP. This standard refers to a real-time transmission of fax documents because the formats for transmitting the signaling and user data between two gateways are described here.
The image data (T.4 or T.6 format) and control messages (T.30 format) are packed in special T.38 messages and sent via the IP network. The packets are either used with TCP (Transmission Control Protocol) or UDP (User Datagram Protocol).
   
At present HG 1500 V3.0 only permits transmission with UDP and not with TCP.  
    The advantage of T.38 is that it is more resistant to
packet loss and jitter in less than perfect network conditions. For more information, refer to the service manual.
    The functions were tested on the following devices:
   -   HF 2323
   -   Fax 790
   -   Canon Fax B155
   -   Hewlett-Packard OfficeJet Model 635
   -   OKI OKIFAX 4580
   -   OKI OKIFAX 4550
   -   Samsung SF-350
   -   Philips magic 2 primo
    UDP
    This protocol is an non-secure connection. IP packets are sent without knowing whether they are received. Thus, this procedure has a number of disadvantages. If you are not sure that the information has been received, then greater effort is required to secure this information.
    Security mechanisms
   •  FEC procedure (Forward Error Correction)
     In this procedure, every "mandatory message" is given a number of previously compressed packets. The number of FEC packets sent with the message is indicated in a supplementary field that can change at any time. To enable the remote station better to identify the packet sequence, each "mandatory message" is given a "sequence number".
   •  Redundancy procedure
     In this procedure, additional IFP pages are sent with a "mandatory message". The number of "redundancy messages" is defined in advance and cannot change during transmission. The "mandatory message" is given a "sequence number" to enable the packets to be identified clearly.

HiPath 3000/5000 V9, Service Documentation, Issue 10   up Top
Disclaimer & Copyright   ID: P31003H3590S100017620   2014-02-27