Task 6.2 PIM DR

In the solution guide for section 6.2 why do we need to set the pim dr-priority to 10000?

Does it matter if R2 is the DR or R7?

 

interface FastEthernet1/0

ip pim sparse-mode

ip pim dr-priority 10000

 


Thanks,

Graham

Comments

  • It worked for me without making DR  R2. The ideea is :

    We have a DR on a multiaccess segment. The DR is responsible for sending the Register Messages to the RP.

    If in the DR is the source of the multicast flow then it will not send the Register message to RP so the RP won't know about the flow.

     

    Ovidiu

  • Hi Ovidiu,

    Can you elabrate a little more? If R7 was the DR,
    it would be the DR of the multicast flow because the source would be
    10.1.27.7 (we pinged from R7 to 224.8.8.8). Should R2 (RP) wooldn't
    know about the flow? But when I made R7 the DR and checked R2, I got the following:

    Rack1R2#sh ip pim vrf 65001 nei

    PIM Neighbor Table

    Neighbor          Interface                Uptime/Expires    Ver   DR

    Address                                                            Prio/Mode

    10.1.27.7         FastEthernet1/0          02:31:04/00:01:27 v2    10000/ DR S

    131.1.4.4         Tunnel1                  02:30:38/00:01:28 v2    1 / DR S

    Rack1R2#sh ip pim vrf 65001 rp

    Group: 224.8.8.8, RP: 10.1.27.2, next RP-reachable in 00:00:08

    Group: 224.0.1.40, RP: 10.1.27.2, next RP-reachable in 00:00:33

    R2 does know about the flow.

    thx.

     

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