DIRECT  INTERNET  ACCESS (DIAS)

What is it?

* Offers a wire-line solution for high-speed symmetrical Internet aaccess on the existing telephone lines.

* Provides an “Always On” Internet Access that is permanently available at the customer's premises.

 

* Combines voice and Internet data packets on a single twisted-pair  wire
   at the subscriber’s premises

 

Schematic diagram of a DIAS system:

 

What does it have ?
 

    • Functions of IAN
     

    • Separates Voice and Data traffic from a number of subscribers ( 60 in each IAN  )
    • Routes independently to the PSTN ( over V 5.2 ) and  Internet respectively (E1 data  ports or Ethernet ports ) using E1 links.
    • Acts as an access unit of the Exchange and provides all the features and services of the Exchange to the Subscriber.
    • Provides 64 Kbps / 128 Kbps connectivity to the Internet via one E1 link ( maximum concentration of 8 : 1 ).

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    What does the IAN do
     
    • v Separates the Voice traffic and the Internet traffic
    • The voice traffic from each BDSU/ HDSU is circuit switched on demand to one of the 64kbps slots on E1 lines connected to an Exchange
    • The protocol used between the IAN and the switch is the  standard V5.2.  optionally the IAN can have a SMUX unit, which would connect  the DIAS subscriber to  the exchange on 2-W interface

      

    Thus, the IAN acts as an ACCESS UNIT of the exchange and provides the services of the Exchange to the subscriber.

    The Internet traffic from each BDSU/HDSU is concentrated at the IAN (IAN essentially acts as a Remote Access Server – RAS, at this point) and passed on to the ISP on a 10 Mbps Ethernet or an E1 leased line. Up to two such E1 ports are provided on the IAN for connection to the ISP.

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    Integrated Access Node (IAN) at the Exchange

    • Separates voice and data traffic from a number of subscribers
    • Routes them independently to the PSTN and the Internet   respectively.
    • Connected to the PSTN via an E1 voice ports to the Internet  either through E1 data ports or through an Ethernet port.
    • Protocol used between the IAN and the switch is the ITU  standard V5.2
    • Voice traffic from each BDSU is circuit switched on demand to one of the 64kbps slots on E1 lines connected to an Exchange essentially acts as a Remote Access Server – RAS, at this point) line. Up to two such E1 ports are provided on the IAN for  connection to the ISP
    • Internet traffic from each BDSU/HDSU is concentrated at the  IAN.
    • Multiple IANs could also be cascaded at the Exchange premises.

       

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    What is a BDSU ?
     
    Basic Digital Subscriber Unit
    • dDsigned for the SOHO (Small Office Home Office) and the  residential Internet user.
    • - Provides a permanent Internet connection at a maximum data   rate of 128 kbps, which drops to 64 kbps when the telephone is in   use and transprently goes back to 128 kbps when the telephone   goes on-hook. 
    • - Located at the subscriber's premises has a telephone interface    (RJ11) and an Ethernet port (RJ45) to provide Internet Access.
    • - Has local powering off the AC Mains (110V/230V) and a backup    battery to support the telephone on power failure.
    • - Ethernet port providing Internet access is off during power   failure.
    Typically, the battery back up gives 8 hrs of standby time and 4 hrs of talk time.

     

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    Basic Digital Subscriber Unit ( BDSU)

    • Combines voice and Internet data packets on a single twisted-pair wire at the subscriber’s premises.
    •  Provides a permanent Internet connection at a maximum data rate of 128 kbps, which drops to 64 kbps when
      the telephone is in use and  transparently, goes back to 128 kbps when the telephone goes on-  hook.
    • Located at the subscriber's premises has a telephone interface (RJ11) and an Ethernet port (RJ45) to provide Internet Access. has local powering off the AC Mains (110V/230V) and a backup
    •  battery to support the telephone on power failure. The Ethernet port  providing Internet access is off during power failure. Typically, the attery back up gives 8 hrs of standby time and 4 hrs of talk time.
    •  connected to the Integrated Access Node, located either at a street corner (curb) or at the Exchange, using a twisted pair copper wire.
    • the maximum length of the copper can be 5 km when 0.5-mm twisted pair copper is used.
    •  has a minimum routing function built-in and routes the packets on the  Ethernet meant for ISP on to the IAN.

       

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    What is a HDSU ?

     

     
    High bit rate Digital Subscriber Unit
    • -Designed for Corporate subscribers .
    • -Can provide voice connectivity for up to 8 telephones and - permanent data connectivity of up to 2 Mbps, which drops to 512Kbps when all the 8 telephones are in use.
    • - Has an Ethernet port and 4/8 Telephone Interfaces (RJ11 ) thus having the ability to connect to 4 or 8 independent  telephones at a Corporate office.

       

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     Connection of BDSU and HDSU
     
    BDSU and the HDSU - connected to the Integrated Access Node ( IAN ) located either at a street corner (curb) or at the Exchange, using a twisted pair copper wire.
    BDSU – Max. length of the copper can be 5 km when 0.5-  mm twisted pair copper is used.
    HDSU
    • - Connected using copper to the IAN.
    •  Maximum rate at which Internet Access is provided to the
    •  HDSU Ethernet port is 2 Mbps
    •  Length of the copper < 2.5 Km (0.5mm twisted pair copper)
    •  the bit-rate on the HDSU–IAN link drops for higher lengths of copper, thus  reducing Internet access rate on the HDSU  Ethernet port. 
    Both the HDSU and the BDSU have a minimum routing function built-in and routes the packets on the Ethernet meant for ISP on to the IAN.
     

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