3Com Switch 8800 Advanced Software V5 Configuration Guide

508 CHAPTER 38: MULTICAST ROUTING AND FORWARDING CONFIGURATION
Before configuring multicast routing and forwarding, prepare the following data:
■ The maximum number of downstream nodes for a single route in a multicast
forwarding table
■ The maximum number of routing entries in a multicast forwarding table
■ The multicast forwarding range
Configuring Multicast
Static Routes
Based on the application environment, a multicast static route has the following
two functions:
■ Changing an RPF route. If the multicast topology structure is the same as the
unicast topology in a network, the delivery path of multicast traffic is the same
as in unicast. By configuring a multicast static route, you can change the RPF
route so as to create a transmission path that is different from the unicast
traffic transmission path.
■ Creating an RPF route. When a unicast route is interrupted, multicast traffic
forwarding is stopped due to lack of an RPF route. By configuring a multicast
static route, you can create an RPF route so that a multicast routing entry is
created to guide multicast traffic forwarding.
Follow these steps to configure a multicast static route
c
CAUTION: When configuring a multicast static route, you cannot designate an
RPF neighbor by specifying an interface (by means of the interface-type
interface-number command argument combination) if the interface type of that
device is VLAN-interface; instead, you can designate an RPF neighbor only by
specifying an address (rpf-nbr-address).
Configuring a Multicast
Route Match Rule
In RPF route selection, the device chooses an optimal route from the multicast
static routing table and the unicast routing table respectively, and then selects the
superior route from these two routes. RPF route selection falls in two cases:
■ If the device is configured to use longest match for route selection, then:
1 The device selects the longest match route from the two routes;
2 If these routes have the same mask, the route with a higher priority will be
selected;
3 If these routes have the same priority, the multicast static route will be selected.
To do... Use the command... Remarks
Enter system view system-view -
Configure a multicast static
route
ip rpf-route-static
source-address { mask |
mask-length } [ protocol [
process-id ] ] [ route-policy
policy-name ] {
rpf-nbr-address |
interface-type
interface-number } [
preference preference ] [
order order-number ]
Required
No multicast static route is
configured by default.