IP Multicast in a Campus Network
HSRP and IP Multicast—HSRP Priority Changed
HSRP standby non-DR
Designated router-highest IP address WINS
CallManager with MoH The following example shows the configuration of Switch 2:
interface Vlan10 description To Server-Farm MoH Server ip address 10.5.10.3 255.255.255.0 ip pim sparse-mode standby 10 priority 120 preempt standby 10 ip 10.5.10.1
The following example shows how to verify that the switch is the HSRP active device:
switch2#show standby brief P indicates configured to preempt.
Group addr 10.5.10.1
The following example shows how to verify that the switch is the PIM DR for the subnet:
switch2#show ip pim interface vlan10
Trace routes should show that unicast traffic is flowing through Switch 2. The mtrace and show ip multicast active commands should show that the multicast traffic is also flowing through Switch 2.
In some situations, there may be a desire to load-balance over the two links from the access layer to the distribution layer. If this is the case, simply ensure that the HSRP Active router is not the DR for the VLAN. For this configuration, which is counter to the one recommended above, give the HSRP Active router the lower IP address of the two distribution switches to ensure that it is selected as the DR.
Cisco AVVID Network Infrastructure IP Multicast Design