LANCOM 1751 UMTS
Chapter 1: Introduction
11
EN
More secure than ISDN or analog: If physical damage should be the cause
of ADSL-line failure then the ISDN/analog line will generally have been
damaged at the same time because both methods use the same physical
cable.
Cheaper than ISDN: Depending on the tariff, monthly running costs for
mobile telephony can be significantly lower than the costs for an ISDN
connection. As actual downtimes of ADSL connections typically add up to
just a few hours a year, the relatively high connection costs for mobile
telephony are simply not relevant. According to needs, billing can be
based on data volume instead of time.
1.1.2
Backup via ISDN direct dial connection
In the case that a branch office is connected to the headquarters via a VPN
connection, it may well be worthwhile for the Internet-based VPN connection
to be backed up by a direct ISDN dial-in connection in addition to the UMTS/
HSxPA backup. Should the provider's network or the Internet connection to
the headquarters fail, then data transmission can be continued over the ISDN
coupling.
1.1.3
Backup with VRRP
A sophisticated backup system for protection against router hardware failure
can be implemented with VRRP. Two or more routers are installed in a net-
work, one of which can replace the other in case of device failure. In addition
to normal VRRP, LANCOM devices can link the backup event triggering func-
tion to the availability of a data connection. With this additional feature,
LANCOM devices with more than one WAN interface (e.g. DSL and UMTS/
HSxPA interface) can be implemented flexibly in backup solutions. The backup
event is triggered for example, when the default route is no longer available
HEADQUARTER
VPN GATEWAY
SERVER
UMTS ROUTER
INTERNET
BRANCH OFFICE
ADSL
ISDN
NETWORK
LAN
110584_LC-1751-UMTS-MANUAL-EN.book Page 11 Tuesday, February 26, 2008 5:16 PM
