However, at times, the traffic volume can simply be in a short lull. Indeed, LAN traffic is
bursty--quiet times followed by an explosion of traffic.
dialer idle-timeout command. Executing this command dictates that when traffic defined as
interesting has ceased to flow across the link for the specified period of time (in seconds), go
ahead and bring down the link. For instance, if the command dialer idle-timeout 180 is used
at the interface configuration mode, the link comes down three minutes after the last piece of
interesting traffic has traversed the link. Note that only interesting traffic resets the timer. Any
non-interesting traffic goes across, but does not contribute to keeping the link up.
informs the switch of the purchased feature set for the particular installation. These SPIDs are
not standardized in their format. The telco provider specifies the use of SPIDs and the appropriate
values, if necessary.
have an optional parameter at the end known as ldn. This is the local dial number. As stated, it
is optional; however, it has been found that in some implementations, the circuit does not
perform optimally in the absence of the ldn parameter. In addition, although it doesn't hurt to
have the ldn parameter on the command line, it can hurt sometimes not to have it.
switch is programmed to look for them (the telco will inform you of this). If they are expected
and not specified, the circuit may not come up. This lack of coming up can be seen in the show
isdn status command under the Layer 2 status section. It shows invalid ldn and spid invalid.
Obviously the circuit is not initialized in this state.
specified callers. The isdn answer command is used for this purpose. The configuration is quite
simple. Once this command has been issued, the router only accepts calls from numbers that
have been specified. Use of this feature combats unauthorized use of the facilities.
command, call screening, and dialer maps.