Manual
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235 
Switch(config)#interface vlan 2 
Switch(Config-If-Vlan2)# ip pim sparse-mode 
Switch(Config-If-Vlan2)#exit 
Switch(config)#interface vlan 3 
Switch(Config-If-Vlan3)# ip pim sparse-mode 
Switch(Config-If-Vlan3)#exit 
Switch(config)#access-list 1 permit 224.1.1.1 0.0.0.255 
Switch(config)#ip multicast ssm range 1 
28.6.4 PIM-SSM Troubleshooting 
In  configuring  and  using  PIM-SSM  Protocol,  PIM-SSM  Protocol  might  not  operate  normally 
caused by physical connection or  incorrect configuration.  Therefore, the  user  should  pay 
attention to the following issues: 
Assure that physical connection is correct; 
Assure the Protocol of Interface and Link is UP (use show interface command); 
Assure that PIM Protocol is enabled in Global Mode (use ip pim multicast-routing); 
Assure that PIM-SSM is configured on the interface (use ip pim sparse-mode); 
Assure that SSM is configured in Global Mode; 
Multicast  Protocol  requires  RPF  check  using  unicast  routing,  therefore  the  correctness  of 
unicast routing must be assured beforehand. 
If all attempts including check are made but the problems on PIM-SSM can’t  be  solved yet, 
then use debug commands such debug pim event/debug pim packet please, and then copy 
DEBUG information in 3 minutes and send to Technology Service Center. 
28.7 DVMRP 
28.7.1 Introduction to DVMRP 
DVMRP  Protocol,  namely,  is  “Distance  Vector  Multicast  Routing  Protocol”.  It  is  a  Multicast 
Routing Protocol in dense mode, which sets up a Forward Broadcast Tree for each source in a 
manner similar to RIP, and sets up a Truncation Broadcast Tree, i.e. the Shortest Path Tree to 
the source, for each source through dynamic Prune/Graft. 
Some of the important features of DVMRP are: 
The routing exchange used to determine reverse path  checking  information is  based on 
distance vector (in a manner similar to RIP) 
Routing exchange update occurs periodically (the default is 60 seconds) 
TTL upper limit = 32 hops (and that RIP is 16) 
Routing update includes net mask and supports CIDR 
In comparison with Unicast routing, Multicast routing is a kind of reverse routing (that is, what 










