IP PIM Multicast RP algorithm selection

[Map23]

Hi community, 

could someone explain me which is algorithm selection for multicast group when 2 RP are configured.

If i remember well (sorry I didn't find nothing on Internet), RP with highest IP address wins, right ?

For example: 

ip access-list standard RP-TEST-01
permit 239.121.1.0 0.0.0.255

ip pim rp-address 1.1.1.1 RP-TEST-01 override

ip pim rp-address 2.2.2.2 RP-TEST-01 override

RP 2.2.2.2 wins, right ?

Another thing, what happen if defined groups for second RP are a subgroup of first RP.

Example: 

ip access-list standard RP-TEST-01
permit 239.121.1.0 0.0.0.255

ip access-list standard RP-TEST-02
permit 239.121.1.0 0.0.0.127

ip pim rp-address 1.1.1.1 RP-TEST-01 override

ip pim rp-address 2.2.2.2 RP-TEST-02 override

Which is the RP for group "239.121.1.0" ? 

Thank you for your help, 

Marcello

[mlund]

Hi Marcello

Yes, You are right, the the highest ip address wins.For the next question, there is a longest match function.Therefore 2.2.2.2 is chosed for groups in the range 239.121.1.0 to 239.121.1.127

For groups in the range 239.121.1.128 to 239.121.1.255 1.1.1.1 is rp

/Mikael

[Map23]

Thank you mlund,
I tried it, but RP selected is 1.1.1.1 for group 239.121.1.1.
But I did a quick test (maybe something wrong). I'll try a better test and I'll post results.

Thanks.

[Map23]

Hi Mikael,
I tried better solution with small ACL but it doesn't working.
RP with high IP address is always chose. In my test environment IOS version is 15.0(2)SE5.
Maybe longest match is valid for old IOS ... With my test IOS only high IP address is evaluated.

Thanks,
Marcello