Specifications

AVM Access Server – Glossary 135
The responses are therefore “spoofed”, or generated at the local end
using the remote client’s source address. If the ISDN connection is
physically active, the packets can be sent over the ISDN line. As soon
as the physical connection is interrupted by the inactivity timeout, and
as long as the logical ISDN connection persists, the remote access soft-
ware answers the packets locally, simulating the existence of a physi-
cal connection to the remote site. Once the physical ISDN connection
has been dialed up again due to user data, spoofing stops and the
overhead packets are transported over ISDN again.
The spoofing mechanisms to be used are negotiated with the remote
client on connection set-up in accordance with the PSCP Draft. If the re-
mote client does not support spoofing, the function is not activated.
Subnet mask
Subnet masks are used in “classless inter-domain routing” (CIDR) to
define a non-standard boundary between the host address and net-
work address components of an IP address. The network address is the
part of the address that is the same for all nodes in a network. The sub-
net mask is composed of ones in the positions of all network address
bits and zeroes in the positions of all host address bits. Subnet masks
are written either in dotted-decimal notation, like the IP address itself
(example: 192.168.10.1/255.255.255.0), or simply as the number of
one-bits in the mask (192.168.10.1/24). For example, a Class A Internet
address, which has a standard network address component of eight
bits (i.e., the subnet mask 255.0.0.0), can be used with a subnet mask
of 16 bits (255.255.0.0) as a quasi-Class B address, or with a 24-bit