74
Step Command Remarks
3. Configure the B channel for
ISDN leased line connection.
dialer isdn-leased
{ number |
128k
}
No B channel on the ISDN BRI
interface is configured for leased
line connection by default.
Configuring permanent link function at ISDN BRI
link layer
With the isdn q921-permanent command, the BRI interface sets up a data link connection
automatically and maintain the connection even when no calls are received from the network layer. If
the two-tei mode is also configured on the interface, two such connections will be present.
To ensure the success of every call attempt, configure permanent Q.921 link mode where the ISDN
NI protocol is adopted.
On PRI interfaces, Q.921 layer negotiates to enter multi-framing state immediately after the user side
and the network side are correctly connected. On BRI interfaces, however, the Q.921 layer transits to
the multi-framing state only after a call is placed and the Q.921 link that has been set up will be torn
down if no Layer 3 call is received before the T325 timer expires.
To configure Q.921 permanent link mode for an ISDN BRI interface:
Step Command Remarks
1. Enter system view.
system-view
N/A
2. Enter BRI interface view.
interface bri
interface-number N/A
3. Set the Q.921 link on the BRI
interface in permanent state.
isdn q921-permanent
The Q.921 links on BRI interfaces
are not in permanent state by
default.
Configuring an ISDN BRI interface to be in
permanent active state on physical layer
This function is available only on the BSV card's network-side BRI interfaces.
On a BRI interface operating on the network side, the T325 timer is triggered when the link is torn
down on data link layer and deactivating requests are sent from data link layer to physical layer when
the timer expires. Deactivating request cause the BRI interface to turn to inactive mode on physical
layer and helps reduce power consumption. To make a BRI interface remain in the active state on
physical layer even if no link exists on the data link layer, you can perform the operations listed in the
following table, through which you can disable activating request sending.
This function is different from the permanent link function. The former maintains the active state of
BRI interfaces on physical layer and is only applicable to BRI interfaces operating on the network
side. It cannot activate the BRI interfaces that are in inactive state on physical layer. The latter,
however, enables BRI interfaces to enter Q.921 multi-framing state immediately after the user side
and the network side are connected correctly. It is only applicable to BRI interfaces operating on the
user side. If you enable the permanent link function when no Q.921 link is established, the system
attempts to establish Q.921 links.
To configure an ISDN BRI interface to be in permanent active state on physical layer:
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