Remote Access Server
Remote Access Server |
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The Windows 2000 remote access server also supports the forwarding of IP multicast traffic between remote access clients and the networks to which the remote access server is attached.
IP multicast support for remote access clients requires the following three elements, as illustrated in Figure 7.17.
Figure 7.17 Multicast Support for Remote Access
For more information about IP multicasting and its support in Windows 2000 Server, see "IP Multicast Support" in this book.
Note
Depending on your choices when running the Routing and Remote Access Server Setup Wizard, IGMP router mode and IGMP proxy mode may already be enabled on the appropriate interfaces.
To facilitate the forwarding of IP multicast traffic from multicast sources on the IP multicast–enabled network to remote access clients:
Remote access clients register the IP multicast addresses from which they want to receive traffic by sending IGMP Membership Report messages across the remote access connection. The remote access server records the multicast groups registered by each remote access client and then forwards the IGMP Membership Report message using the interface on which IGMP proxy mode is enabled.
The forwarded IGMP Membership Report message is received by the IP multicast routers attached to the remote access server's network segment. The IP multicast routers of the IP multicast–enabled network use multicast routing protocols to create entries in their multicast forwarding tables, so that multicast traffic sent to the multicast groups — registered by the remote access clients — are forwarded to the network segment of the remote access server.
When the multicast source sends multicast traffic to the multicast group registered by the remote access clients, IP multicast routers forward the multicast traffic to the network segment of the remote access server for the interface on which IGMP proxy mode is enabled.
When the remote access server receives multicast traffic on the interface on which IGMP proxy mode is enabled, the multicast traffic is checked to determine whether any connected remote access client has registered an IGMP Membership Report for that multicast group. If the multicast traffic corresponds to a multicast group registered by a remote access client, the multicast traffic is forwarded to the remote access client.
To facilitate the forwarding of IP multicast traffic from remote access clients that are multicast sources:
Hosts on the IP multicast–enabled network register the IP multicast addresses for which they want to receive traffic from by sending IGMP Membership Report messages on their local network segments. The IP multicast routers of the IP multicast–enabled network use multicast routing protocols to create entries in their multicast forwarding tables. Therefore, multicast traffic sent to the multicast groups registered by the hosts are forwarded to the host's network segment.
When the remote access client sends multicast traffic across the remote access connection, the multicast traffic is forwarded to the network segment of the interface on the remote access server enabled for IGMP proxy mode. IP multicast routers on that network segment receive the forwarded multicast traffic and forward it to the network segments of the group members.
Additionally, the remote access server forwards the IP multicast traffic to other remote access clients that are listening for the IP multicast traffic of the remote access client that is the multicast source.
If the remote access server is being used to provide Internet access to dial-up clients, then the following configuration allows IP multicast traffic to and from connected remote access clients:
If the remote access server is being used to provide a connection to an organization's intranet to dial-up or VPN clients, then the following configuration allows IP multicast traffic to and from connected remote access clients:
