3-2 ISDN

  • Primary Rate Interface (PRI) has 23 B (bearer) channels and one D (data) channel in North America and Japan, and 30 B channels and one D channel in the rest of the world. These are usually known as the 23B+D and 30B+D formats.

  • Each B channel carries a 64 kbps timeslot (data or voice).

  • The D channel is also a 64 kbps timeslot, carrying signaling for all the B channels. On a 23B+D PRI, the D channel is found in channel 23. On a 30B+D PRI, it is in channel 15.

  • Digital calls over a B channel are handled by the ISDN processor in the router, and analog modem calls are handled by the on-board modems in the router.

  • Basic Rate Interface (BRI) has two B channels and one D channel. Each B channel is 64 kbps, and the D channel is 16 kbps, for a total of 144 kbps. This is known as the 2B+D format.

  • BRI interfaces can use a service profile identifier (SPID) number for identification. It is assigned by the service provider.

PRI Configuration

  1. Set the global ISDN switch type for all PRI interfaces:

     (global)  isdn switch-type   switch-type  

    The ISDN switch-type must be set to match the switching equipment being used by the telephony provider. In North America, use basic-5ess (Lucent basic rate switches), basic-dms100 (NT DMS-100 basic rate switches), or basic-ni1 (National ISDN-1). In Australia , use basic-ts013 (TS013). In Europe, use basic-1tr6 (German 1TR6), basic-nwnet3 (Norwegian NET3 phase 1), basic-net3 (NET3), vn2 (French VN2), or vn3 (French VN3). In Japan, use ntt (NTT). In New Zealand, use basic-nznet3 (New Zealand NET3).

    NOTE

    To use QSIG signaling, use a switch-type of basic-qsig.

  2. Configure the T1/E1 controller.

    1. Select the controller:

       (global)  controller  {  t1   e1  }  slot/port  

      -OR-

       (global)  card type  {  t1   e1  }  slot  

      A T1/E1 controller is referenced by controller and slot and port number on 2600 and 3600 routers and by card type and slot number on 7200, 7500, and AS5x00 routers and access servers.

    2. (Optional) Set the ISDN switch type for this PRI:

       (global)  isdn switch-type   switch-type  

      The switch type can also be set on a per-PRI basis, overriding the global switch type.

    3. Set the framing type:

       (controller)  framing  {  sf   esf   crc4   no-crc4  } [  australia  ] 

      The T1 framing type can be sf (super frame, the default) or esf (extended super frame). The E1 framing type can be crc4 (the default), no-crc4, and an optional australia.

    4. Set the clock source:

       (controller)  clock source  {  line  [  primary   secondary  ]  internal  } 

      The controller can derive its clock from line (CO or external source) or internal (the controller's internal clock). A line clock can be designated as primary (preferred over other controllers' line clocks) or secondary (used as a backup external clock source).

    5. Set the line encoding:

       (controller)  linecode  {  ami   b8zs   hdb3  } 

      For a T1, the line coding can be set to ami (the default) or b8zs (binary 8 zero substitution). For an E1, it can be set to ami or hdb3 (the default; high-density bipolar 3).

  3. Configure the PRI group :

     (controller)  pri-group  [  timeslots   range  ] 

    The voice timeslots are identified as a range ( numbers 1 to 23 or 1 to 30, separated by a dash or comma). If the timeslots and range keywords are not used, the default is a PRI with 23 B channels and one D channel.

    NOTE

    To reference the serial interfaces corresponding to the PRI channels, use i nterface serial controller:channel, where controller is the T1 controller number for the physical connection and channel is 0 to 22 for B channels 1 to 23 and 23 for the D channel. (Interface channel numbering begins at 0, and T1/E1 channel numbering begins at 1.) For an E1 controller, the channel is 0 to 30 for B channels and 15 for the D channel.

    When you are configuring a PRI for dial- related features, always configure the features on the D channel.

  4. (Optional) Set the B channel ordering for outgoing calls.

    1. Select the D channel interface:

       (global)  interface serial   controller:  [  23   15  ] 

      The D channel is identified as channel 23 for a T1 PRI and channel 15 for an E1 PRI.

    2. Set the order:

       (interface)  isdn bchan-number-order  {  ascending   descending  } 

      The first available B channel can begin with B1 in ascending order or B23/B30 in descending order (the default). Make sure the order used matches that of your service provider.

  5. Set other optional parameters.

    1. (Optional) Use TEI negotiation:

       (interface)  isdn tei  [  first-call   powerup  ] 

      By default, TEI negotiation occurs when the router is powered up ( powerup ). In Europe or when connecting to a DMS-100 ISDN switch, you might need to perform the negotiation during the first active call ( first-call ).

    2. (Optional) Send a calling number with outbound calls:

       (interface)  isdn calling-number   calling-number  

      The calling-number (a string of digits) represents a telephone number to be used as a billing number by the service provider.

PRI Example

A T1 controller is configured for ISDN PRI use. ESF framing and B8ZS line coding are used. The clock source is the line, and controller T1 0 is the primary source. The PRI consists of timeslots 1 to 24 (the entire T1 format), with the D channel on timeslot 24 (or interface channel 23).

  controller T1 0   framing esf   clock source line primary   linecode b8zs   pri-group timeslots 1-24   interface serial 0:23  

BRI Configuration

  1. Set a global ISDN switch type for all BRI interfaces:

     (global)  isdn switch-type   switch-type  

    The ISDN switch-type must be set to match the switching equipment being used by the telephony provider. In North America, use basic-5ess (Lucent basic rate switches), basic-dms100 (NT DMS-100 basic rate switches), or basic-ni1 (National ISDN-1). In Australia, Europe, and the UK, use basic-1tr6 (German 1TR6), basic-net3 (NET3), or vn3 (French VN3). In Japan, use ntt (NTT). All other areas should use none (no specific definition).

  2. Select a BRI interface:

     (global)  interface bri   number  

    The BRI number is the physical location on the router.

  3. (Optional) Set the ISDN switch type for the BRI:

     (global)  isdn switch-type   switch-type  

    The selected BRI interface can have its own switch type configured, overriding the global switch type.

  4. (Optional) Use SPIDs:

     (interface)  isdn spid1   spid-number  [  ldn  ] (interface)  isdn spid2   spid-number  [  ldn  ] 

    If your ISDN service provider assigned SPIDs to your BRI, you must configure them on the BRI interface. One or two SPIDs can be assigned as spid-number, usually a seven-digit telephone number with additional optional numbers. DMS-100 and NI1 ISDN switch types require SPIDs, whereas they are optional on the 5ESS type. The service provider might also assign local directory numbers (ldn), to be used when answering incoming calls.

  5. Set other optional parameters.

    1. (Optional) Use TEI negotiation:

       (interface)  isdn tei  [  first-call   powerup  ] 

      By default, TEI negotiation occurs when the router is powered up ( powerup ). In Europe or when connecting to a DMS-100 ISDN switch, you might need to perform the negotiation during the first active call ( first-call ).

    2. (Optional) Screen incoming calls for one or more numbers:

       (interface)  isdn caller   number  

      If the local ISDN switch can send caller ID (CLID) information, you can specify calling numbers that will be accepted. number (up to 25 digits; X is a wildcard digit) is an accepted calling telephone number.

    3. (Optional) Verify the called party number:

       (interface)  isdn answer1  [  called-party-number  ] [:  subaddress  ] (interface)  isdn answer1  [  called-party-number  ] [:  subaddress  ] 

      If more than one device is attached to a BRI, the router answers only calls that are destined for either the called-party-number (up to 50 digits; X is a wildcard digit) or the ISDN : subaddress (a colon followed by a subaddress string of up to 50 digits; X is a wildcard), or both.

    4. (Optional) Send a calling number with outbound calls:

       (interface)  isdn calling-number   calling-number  

      The calling-number (a string of digits) represents a telephone number to be used as a billing number by the service provider.

    5. (Optional) Set a fast rollover delay to release a B channel:

       (interface)  isdn fast-rollover-delay   seconds  

      If a new ISDN call fails because a previous call hasn't yet been torn down, set the delay to seconds (usually 5 seconds is sufficient).

    6. (Optional) Send a disconnect cause code to the ISDN switch:

       (interface)  isdn disconnect-cause  {  cause-code-number   busy   not-available  } 

      By default, when a BRI connection ends, the ISDN application sends a default cause code. You can override this with a specific cause-code-number (1 to 127), busy (the USER-BUSY code), or not-available (the CHANNEL-NOT-AVAILABLE code).

    7. (Optional) Bind a DNIS to an ISDN subaddress:

       (interface)  dialer called   DNIS:   subaddress  

      If it is necessary to identify a DNIS number with a specific ISDN subaddress, both can be specified as DNIS: subaddress. This is sometimes required in Europe and Australia.

BRI Example

Two ISDN BRI interfaces are used on a router. A global ISDN switch type is set for a 5ESS. Interface BRI 0 uses the default switch type, with no SPID numbers. Interface BRI 1, however, has another switch type defined for a DMS-100. Two SPIDs are configured for the two B channels:

  isdn switch-type basic-5ess   interface bri 0   ip address ...   interface bri 1   isdn switch-type basic-dms100   isdn spid1 555123401   isdn spid2 555123402   ip address 192.168.71.45 255.255.255.0  


Cisco Field Manual[c] Router Configuration
Cisco Field Manual[c] Router Configuration
ISBN: 1587050242
EAN: N/A
Year: 2005
Pages: 185

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