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Bronze

PIM Dense: question of the output of "show ip mroute"

Hi everyone,

I have a question of the output of "show ip mroute" command.

We configure PIM Dense multicast network with redundancy environment, which means that

each PIM Dense router(L3 switch) has more than two equal cost paths to multicast sender.

In this environment, RPF nbr information from "show ip mroute" changes periodically

between two upstream PIM Dense routers(L3 switches)

The following is the output of "show ip mroute" command.

- First time

(xxx.xxx.xxx.xxx, 239.1.1.1), 00:02:23/00:00:55, flags: PT

Incoming interface: Vlanxxx, RPF nbr xxx.xxx.xxx.84

Outgoing interface list:

GigabitEthernet1/0/3, Prune/Dense, 00:02:14/00:00:46

Vlanxxx, Prune/Dense, 00:02:23/00:00:37

RPF nbr is xxx.xxx.xxx.84

- Second time

(xxx.xxx.xxx.xxx, 239.1.1.1), 00:02:23/00:00:55, flags: PT

Incoming interface: Vlanxxx, RPF nbr xxx.xxx.xxx.83 *

Outgoing interface list:

GigabitEthernet1/0/3, Prune/Dense, 00:02:14/00:00:46

Vlanxxx, Prune/Dense, 00:02:23/00:00:37

RPF nbr xxx.xxx.xxx.83 *

- Third time

(xxx.xxx.xxx.xxx, 239.1.1.1), 00:02:23/00:00:55, flags: PT

Incoming interface: Vlanxxx, RPF nbr xxx.xxx.xxx.84

Outgoing interface list:

GigabitEthernet1/0/3, Prune/Dense, 00:02:14/00:00:46

Vlanxxx, Prune/Dense, 00:02:23/00:00:37

RPF nbr is xxx.xxx.xxx.84

...

In this output, PRF nbr information changes

RPF nbr xxx.xxx.xxx.84

RPF nbr xxx.xxx.xxx.83 *

RPF nbr xxx.xxx.xxx.84

RPF nbr xxx.xxx.xxx.83 *

.

.

.

I would like to know why RPF nbr information is changed periodically.

And why RPF nbr xxx.xxx.xxx.83 is marked with "*".

I understand that it might be caused due to PIM Dense because PIM Dense works with

flooding and pruning mechanism, but I do not understand why RPF nbr xxx.xxx.xxx.83

is marked with "*".

Your information would be greatly appreciated.

Best regards,

2 REPLIES
Cisco Employee

Re: PIM Dense: question of the output of "show ip mroute"

Hi Friend,

If an asterisk (*) appears after the IP address in this field, the RPF neighbor has been learned through an assert.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124tcr/timc_r/mlt_s1ht.htm#wp1092166

Just scroll down and check the details for particular feild in output of "sh ip mroute"

HTH

Ankur

Bronze

Re: PIM Dense: question of the output of "show ip mroute"

Thank you very much for your information.

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