Specifications

Reserving B Channels
78 AVM Access Server – 5 AVM Access Server Concepts and Functional Principles
Static routing
All information about destination networks and the paths by
which they can be reached is configured manually, and changed
only by the administrator.
Dynamic routing
All routers in the network can exchange information about subnet-
works and the paths to them by means of a routing protocol. Rout-
ers regularly update their own routing tables automatically based
on the information received.
The AVM Access Server uses dynamic routing with RIP 2 (Routing Infor-
mation Protocol, Version 2) on its LAN interfaces, and static routes over
ISDN. The use of static routes over ISDN prevents excessive ISDN calls
due to the exchange of RIP packets. When configuring a remote user or
network, you may choose whether the static route to the user should
always be known in the WAN, or whether it should be known only when
the logical ISDN connection has been set up.
In the former case, a packet addressed to a destination outside the
LAN causes the logical ISDN connection to be set up automatically.
In the latter case, packets can only be sent to a user when a logical
ISDN connection to the remote user or network exists, because this is
the only time the route is known.
5.4 Reserving B Channels
The B channels of all ISDN-Controllers used by the AVM Access Server
are allocated from a common pool to all remote networks and users.
This principle is a flexible basis for optimum utilization of the available
channels. Furthermore, the configuration of remote users and net-
works is thus independent of specific ISDN B channels. (ADSL connec-
tions to remote networks are an exception, since the ADSL line is dedi-
cated to a specific remote network—usually the Internet.)
Furthermore, at any given time there may be more logical ISDN connec-
tions to remote users or networks than there are ISDN B channels avail-
able. This is due to the inactivity timeout which automatically clears
down idle ISDN connections in the background. When a connection is
idle, the AVM Access Server makes the last B channel it used available
for other connections. The physical connection is dialed up again as
soon as data packets are queued for transport to or from the remote
system.