Siemens ADSL 50 - Manual (Page 56)

SANTIS ADSL 50/500 User Manual
Demilitarized Zone (DMZ) allows one IP address (computer) to be exposed to the Internet. Some applications require
multiple TCP/IP ports to be open. It is recommended that you set your computer with a static private IP address if you
want to use DMZ. The DMZ Host settings allow one local user to be exposed to the Internet to use special-purpose
service such as Internet gaming or Video-conferencing. It is strongly recommended that you only define servers as
DMZ host, which do not signify a security risk. To set up a DMZ host proceed as follows:
1. Enter the IP address of your DMZ host and click to Apply.
2. Your designated servers on the LAN are no accessible to the outside.
IGMP Proxy
IGMP proxy enables the system to issue IGMP host messages on behalf of hosts that the system discovered via
standard IGMP interfaces. The system acts as a proxy for its hosts.
If you enable IGMP proxy on your ADSL Router, your ADSL Router is the upstream interface.
On the interfaces connected to your ADSL Router you have to run IGMP. These interfaces are known as downstream
interfaces.
Downstream interfaces connected to the upstream interface (IGMP Proxy) can join for example the same video
stream at the same time. The advantage with the IGMP Proxy is, that the bandwidth of the video stream is only used
once: from the upstream interface to the video server in the Internet. All downstream interfaces will download the
video stream form the IGMP Proxy and not from the Internet directly.
In IGMP operation, hosts interact with the system through the exchange of IGMP messages. Similarly, when you
configure IGMP proxy, the system interacts with the router on its upstream interface through the exchange of IGMP
messages. However, when acting as the proxy, the system performs the host portion of the IGMP task on the
upstream interface as follows:
• When queried, sends group membership reports to the group
• When one of its hosts joins a multicast address group to which none of its other hosts belong, sends unsolicited
group membership report to that group
• When the last of its hosts in a particular multicast group leaves the group, sends an unsolicited leave group
membership report to all-routers group
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