Riverstone Networks WICT1-12 - Manual (Page 466)

19-2 Riverstone Networks RS Switch Router User Guide Release 8.0
Configuring IGMP Multicast Routing Configuration
DVMRP uses the Reverse Path Multicasting (RPM) algorithm to perform pruning. In RPM, a source network rather
than a host is paired with a multicast group. This is known as an (S,G) pair. RPM permits the RS to maintain multiple
(S,G) pairs.
On the RS, DVMRP can be configured on a per-interface basis. An interface does not have to run both DVMRP and
IGMP. You can start and stop DVMRP independently from other multicast routing protocols. IGMP starts and stops
automatically with DVMRP. The RS supports up to 64 multicast interfaces.
To support backward compatibility on DVMRP interfaces, you can configure the router expire time and prune time on
each RS DVMRP interface. This lets it work with older versions of DVMRP.
You can use threshold values and scopes to control internetwork traffic on each DVMRP interface. Threshold values
determine whether traffic is either restricted or not restricted to a subnet, site, or region. Scopes define a set of multicast
addresses of devices to which the RS can send DVMRP data. Scopes can include only addresses of devices on a
company's internal network and cannot include addresses that require the RS to send DVMRP data on the Internet. The
RS also allows control of routing information exchange with peers through route filter rules.
You can also configure tunnels on RS DVMRP interfaces. A tunnel is used to send packets between routers separated
by gateways that do not support multicast routing. A tunnel acts as a virtual network between two routers running
DVMRP. A tunnel does not run IGMP. The RS supports a maximum of eight tunnels.
Note Tunnel traffic is not optimized on a per-port basis, and it goes to all ports on an
interface, even though IGMP keeps per-port membership information. This is
done to minimize CPU overload for tunneled traffic.
19.3 CONFIGURING IGMP
You configure IGMP on the RS by performing the following configuration tasks:
• Creating IP interfaces
• Setting global parameters that will be used for all the interfaces on which DVMRP is enabled
• Configuring IGMP on individual interfaces. You do so by enabling and disabling IGMP on
interfaces and then setting IGMP parameters on the interfaces on which IGMP is enabled
• Start the multicast routing protocol (i.e., DVMRP)
19.3.1 Configuring IGMP on an IP Interface
By default IGMP is disabled on the RS.
To enable IGMP on an interface, enter the following command in Configure mode:
Enable IGMP on an interface.
igmp enable interface
<name/ipAddr>