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Cisco Catalyst Switch Module 3110 and 3012 for IBM BladeCenter Software Configuration Guide
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Chapter 38 Configuring IP Unicast Routing
Configuring Stub Routing
When using PIM stub routing, you should configure the distribution and remote routers to use IP
multicast routing and configure only the switch as a PIM stub router. The switch does not route transit
traffic between distribution routers. You also need to configure a routed uplink port on the switch. The
switch uplink port cannot be used with SVIs.
You must also configure EIGRP stub routing when configuring PIM stub routing on the switch. For more
information, see the “Understanding EIGRP Stub Routing” section on page 38-29 and the “Configuring
EIGRP Stub Routing” section on page 38-30.
The redundant PIM stub router topology is not supported. The redundant topology exists when there is
more than one PIM router forwarding multicast traffic to a single access domain. PIM messages are
blocked, and the PIM assert and designated router election mechanisms are not supported on the PIM
passive interfaces. Only the nonredundant access router topology is supported by the PIM stub feature.
By using a nonredundant topology, the PIM passive interface assumes that it is the only interface and
designated router on that access domain.
In Figure 38-4, Switch A routed uplink port 25 is connected to the router, and PIM stub routing is
enabled on the VLAN 100 interfaces and on Host 3. This configuration allows the directly connected
hosts to receive traffic from multicast source 200.1.1.3. See the “Configuring PIM Stub Routing” section
on page 38-27 for more information.
Figure 38-4 PIM Stub Router Configuration
Configuring PIM Stub Routing
The PIM stub routing feature supports multicast routing between the distribution layer and the access
layer. It supports both uplink PIM interfaces and PIM passive interfaces. A routed interface configured
with the PIM passive mode does not forward PIM control traffic, it only passes and forwards IGMP
traffic.
Source
200.1.1.3
Router
3.1.1.2.255.255.255.0
Switch
A
Host 1 Host 2
VLAN 100 Host 3
Port 15 Port 3
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