Cisco Systems 78-11741-02 manual Udlr Tunnel Configuration Task List, Prerequisite, IPC-508

Configuring Unidirectional Link Routing

UDLR Tunnel Configuration Task List

In the scenario in Figure 82, the following sequence of events occurs:

1.User 1 joins multicast group G.

2.Router C sends a Protocol Independent Multicast (PIM) join message hop-by-hop to the rendezvous point (Router B).

3.Router B receives the PIM join message and adds a forwarding entry for group G on LAN B.

4.Router B periodically checks its mroute table, and forwards an IGMP report for each multicast group in which it is the reporter.

5.Router A creates and maintains a forwarding entry on the UDL.

In an enterprise network, for example, it is desirable to be able to receive IP multicast traffic via satellite and forward the traffic throughout the network. With IGMP UDLR alone, this scenario is not possible because receiving hosts must be directly connected to the downstream router. IGMP Proxy overcomes this limitation by creating an IGMP report for (*, G) entries in the multicast forwarding table. To make this scenario functional, you must configure PIM sparse mode (PIM-SM) in the network, make the UDL downstream router the rendezvous point (RP) for a select set of addresses, and configure mroute proxy on interfaces leading to PIM-enabled networks with potential members. When the UDL downstream router has a (*, G) forwarding entry for an mroute proxy interface, an IGMP report for the group is created and sent to a loopback interface (IGMP Proxy interface). The loopback interface then uses the same mechanism as IGMP UDLR to forward reports upstream.

Note Because PIM messages are not forwarded upstream, each downstream network and the upstream network has a separate domain.

UDLR Tunnel Configuration Task List

To configure a UDLR tunnel, perform the required tasks described in the following section:

•Configuring UDLR Tunnel (Required)

Prerequisite

Before configuring UDLR tunnel, ensure that all routers on the UDL have the same subnet address. If all routers on the UDL cannot have the same subnet address, the upstream router must be configured with secondary addresses to match all the subnets that the downstream routers are attached to.

Configuring UDLR Tunnel

When configuring a UDLR tunnel, you must configure both the upstream and downstream routers to meet the following conditions:

•You need not assign an IP address to the tunnel (you need not use the ip address or ip unnumbered interface configuration commands).

•You must configure the tunnel endpoint addresses.

•The tunnel mode defaults to GRE.

Cisco IOS IP Configuration Guide

IPC-508