Task 5.1 & 5.2 IP Multicast

Not sure if anyone else is doing this currently but my solution differs from the book and I was wondering what other thought.

Requirements:

5.1 RP Assignment
• Discover the active multicast topology using the respective show
commands.
• Configure R3 to announce its most reliable interface as the RP for all
multicast groups using Auto-RP protocol.
• R2 should be responsible for group to RP mappings. 

My solution:

r3

en
conf t
ip multicast-routing
ip pim autorp listener
ip pim send-rp-announce Loopback0 scope 3
ip pim send-rp-discovery Loopback0 scope 3
no ip pim dm-fallback
interface loopback 0
ip pim sparse-dense-mode
end

r2
en
conf t
ip multicast-routing
ip pim autorp listener
ip pim send-rp-discovery serial 0/0/0 scope 3
no ip pim dm-fallback
end

r5
en
conf t
ip multicast-routing
ip pim autorp listener
ip pim send-rp-discovery serial 0/0/0 scope 3
no ip pim dm-fallback
end

Book Solution

R2:
Configure R2 as the Auto-RP MA
interface Loopback0
ip pim sparse-mode
ip pim send-rp-discovery Loopback0 scope 16

R3:
Configure R3 as the RP advertising itself via Auto-RP

interface Loopback0
ip pim sparse-mode
ip pim send-rp-announce Loopback0 scope 16

My concerns

Now I'm not sure why the MA has to be on the loopback of R2 and also why R3 can not be a mapping agent also.  The way I configured R5 it now knows that R3 is the RP.  I've always worked were everyone the participates in multicast has to know where the RP is.  Not sure why the solution would have R5 not discover the RP.

Now if the above is ok as I do not think I violated any requirements my solution for 5.2 does not need a static mroute as R5 sends the traffic to the RP

Any thoughts or comments are welcome.

Andy

P.S my test for 5.2 with this solution

Rack1R2#ping 226.26.26.26 source 183.1.28.2         

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 226.26.26.26, timeout is 2 seconds:
Packet sent with a source address of 183.1.28.2

Reply to request 0 from 183.1.0.5, 96 ms
Rack1R2#

 

 

 

Comments

  • Your solution indeed works, but you need to follow the task's requirements. It is requesting R3 to be the RP and R2 to be the MA. In your config, you did the MA config on R2, but you also over-configured it on R3. 

    Also the loopback is used, as this is the most reliable interface and allow the MA to remain up in case you have redundancy.

    HTH

    Good luck!

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