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same time), one call is completed and other call is cleared. The
direction of precedence is not important, but it must be set to
IN at one end of the call and OUT at the other end of the call.
The ISDN number is the exact sequence required to reach the
remote router from the local router, including STD access
codes and area codes. The number may contain only decimal
digits. Hyphens and other characters will result in an error.
Check that the ISDN calls have been successfully added with
the command:
SHOW ISDN CALL
6
Create PPP interfaces to use the ISDN calls. PPP provides
the link layer protocol and enables multiple network and
transport layer protocols such as IP and Novell
®
IPX to be
carried over the same ISDN link.
For example, on the Head Office router create PPP interface 0
to use the ISDN call ROHO:
CREATE PPP=0 OVER=ISDN-ROHO
On the Remote Office router, create PPP interface 0 to use the
ISDN call ROHO:
CREATE PPP=0 OVER=ISDN-ROHO
Check the configuration with the commands:
SHOW ISDN CALL
SHOW PPP
The call ROHO should appear in the output of the SHOW
ISDN CALL command. The output of the SHOW PPP
command should show interface ppp0 over ISDN-ROHO.
ISDN is now ready to be used by routing protocols such as IP
and IPX.
CONFIGURING PRIMARY RATE ISDN
To configure Primary Rate ISDN on the AR745 router, follow
these steps:
1
The AR745 can operate in either TE or NT mode, using 75
Ω
or 120
Ω
termination. The router is shipped with jumpers set to
TE mode, 75
Ω
termination, Tx grounded and Rx grounded via a
100nF capacitor. This is appropriate for most situations. Your
distributor or reseller can advise you whether or not grounding
jumpers should be installed.
Warning: Disconnect the router from the mains power
supply before removing the router lid.
Directory numbers and subaddresses can be entered with
the command:
SET Q931=0 NUM1=
number NUM2=number
SUB1=
subaddress SUB2=subaddress
The directory numbers and subaddresses must be supplied by
the ISDN service provider. If the directory number is a full 10
digit number (3 digit area code plus 7 digit number), the router
will append the digits “0101” to the number and attempt SPID
initialisation with the result. This is known as the Generic SPID
procedure. If SPID initialisation has already taken place and
SPIDs have been obtained through the Auto SPID procedure,
then either these SPIDs are the same as the Generic SPID and
the router will successfully reinitialise, or the SPIDs are not the
same as the Generic SPID and the router will not initialise. In
this case, the router will revert to using the Auto SPID values.
5
Create ISDN call definitions to enable the router to make
ISDN calls to other devices on the ISDN network. This is the
only step that must be completed to configure ISDN on the
router. Before a call can be made from one router to another,
call definitions must be created on both routers, using
the command:
ADD ISDN CALL=
name NUMBER=number
PRECEDENCE={IN|OUT}
options...
For example, a Remote Office router is to be connected to the
Head Office router via ISDN. The ISDN number of the Remote
Office router is 1234567. The ISDN number of the Head Office
router is 9876543. The
called party subaddress information
element
(IE) is used to carry connection information, and PPP
interfaces will be created explicitly to use the ISDN calls. Either
router can initiate the call, but calls from the Remote Office
have precedence. On the Head Office router, create a call to
the Remote Office router:
ADD ISDN CALL=ROHO OUTSUB=LOCAL
SEARCHSUB=LOCAL NUMBER=1234567 PREC=IN
On the Remote Office router, create a call to the Head
Office router:
ADD ISDN CALL=ROHO OUTSUB=LOCAL
SEARCHSUB=LOCAL NUMBER=9876543
PREC=OUT
Each call has the same name (ROHO), and this name is passed
via the called subaddress IE to provide identification to the
remote end of the link. Each router will search for this call
using the called subaddress IE.
The precedence must be set to ensure that in the event of a
call collision (the same call being made and answered at the
