Hi !

I'm in my final preparation of my CCNP certification BSCI exam, my exam is schedule to next Friday, so rapid answer will be appreciated.  For final preparation I had buy How2Pass test exam to test my knowledge before going to the test center.  I find I had some difficulties with IP multicast subject about troobleshooting.....

in the following question (see attach filed ng43.zip)

I answer to this question by :

The RP for this network    ==> because the RPF ip address is set to 0.0.0.0  for the entry (*,224.1.1.1)  the local IP address of this router is : 10.127.0.7 base on RP information

The multicast source of this router is serial 1/4 interface  ==> the incomming interface is serial 1/4 for the entry (172.16.8.1,224.1.1.1)  and the source multicast server will be at the IP address 172.16.8.1 and the next hop to reach this IP address is 10.139.16.130 base on RPF nbr information in this entry.

Because I did not sucessfully answer this question on the first time I also read the link provide on Cisco website for explanation :

http://www.cisco.com/en/US/docs/ios/12_2/switch/command/reference/xrfscmd6.html#wp1056899

which after reading help me to understand some point, but also raised some question.....

in the following output

The following is sample output from the show ip mroute command for a router operating in sparse mode: 
Router# show ip mroute








IP Multicast Routing Table




Flags: D - Dense, S - Sparse, C - Connected, L - Local, P - Pruned




       R - RP-bit set, F - Register flag, T - SPT-bit set




Timers: Uptime/Expires




Interface state: Interface, Next-Hop, State/Mode








(*, 224.0.255.3), uptime 5:29:15, RP is 198.92.37.2, flags: SC




  Incoming interface: Tunnel0, RPF neighbor 10.3.35.1, Dvmrp




  Outgoing interface list:




    Ethernet0, Forward/Sparse, 5:29:15/0:02:57








(198.92.46.0/24, 224.0.255.3), uptime 5:29:15, expires 0:02:59, flags: C




  Incoming interface: Tunnel0, RPF neighbor 10.3.35.1




  Outgoing interface list:




    Ethernet0, Forward/Sparse, 5:29:15/0:02:57

my understanding the RP for the group 224.0.255.3 is 198.92.37.2 and the next hop to RP is 10.3.35.1.  But in the second entry if the group 224.0.255.3 is used in sparse mode why is it not appear the R flag to tell this entry is pointing toward the RP like it is explain in table 45 in the same pages

   R - RP-bit set 
Indicates that the (S, G) entry is pointing toward the rendezvous point (RP). The RP is typically a prune state along the shared tree for a particular source.

also in the table 45 I would like understand the following :

RP 
Address of the rendezvous point router. For routers and access servers operating in sparse mode, this address is always 0.0.0.0.

Base on my understanding the RP this entry will on the IP address of the RP in sparse mode, in dense mode because theire is no RP the value will be set to 0.....  is had in error here ??

also in the following I find some contradiction base on what I had understand :

(*, 224.0.255.1), uptime 0:57:31, expires 0:02:59, RP is 224.0.0.0, flags: DC




  Incoming interface: Null, RPF neighbor 224.0.0.0, Dvmrp




  Outgoing interface list:




    Ethernet0, Forward/Dense, 0:57:31/0:02:52




    Tunnel0, Forward/Dense, 0:56:55/0:01:28

Someone can help me to understand !

Thanks a lot !