IPv6 PIM RP for one group only

[kondratev]

Hello,

I need to configure my router to be RP for 1 group only. It should reject PIM messages for all other groups. I've tried to to the following:

ipv6 pim rp-address XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX ALLOWED_GROUP

!

ipv6 access-list ALLOWED_GROUP

permit ipv6 any host FF08:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY

where XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX - is one of my router's IPv6 addresses that I wish to be RP,

FF08:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY - is IPv6 group that I need to allow.

But when I enter the command 'FF08:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY', I see the following message: "%Error: Group prefix must be less than 128, skipping FF08:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY/128".

Could you please suggest me how can I allow one group only?

[Solomon Sudhakar]

Hi,

Use acl as shown below instead of host

ipv6 access-list ALLOWED_GROUP

permit ipv6 any FF08:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY:YYYY/127

Regards,

Solomon

[Peter Paluch]

Hi Solomon,

But this is interesting - it's been discussed here already and no reasonable answer was given as of yet. What is the reason that you are not allowed to configure an IPv6 PIM-SM RP for a single group? Is this a technical issue of some sort? It just doesn't make sense.

Best regards,

Peter

[Solomon Sudhakar]

Hi Peter,

Unfortunately an access-list cannot specify a permit entry for a *single* v6 multicast group. This is a general IOS limitation for now.

Regards,

Solomon

[Peter Paluch]

Hello Solomon,

Thank you for answering!

Unfortunately an access-list cannot specify a permit entry for a  *single* v6 multicast group. This is a general IOS limitation for now.

Exactly, and I am interested in knowing if this limitation is caused by any reasonable technical cause, or whether it is just some (obviously unfortunate) design choice that could be remedied by a relatively simple correction in IOS's source code.

Best regards,

Peter