Re: Mcast RP redundancy Question

Hi,

On Tue, Apr 14, 2009 at 5:03 PM, Naveen <navin.ms_at_gmail.com> wrote:
>
> *Task*: R1 and R2 should be the RPs for their respective groups, but each
> should serve as a backup for other.
>
> *Question is* - which protocol should I use to provide redundancy ? BSR,
> Auto-RP or Anycast RP ?
>
> *1) In Auto-RP: *
> Let R1 and R2 announce themselves as RPs for entire 224.0.0.0/8, but have
> the MA select R1 for first set and R2 for second set.
> If either R1 or R2 is dead, the MA will select the other as the RP for all
> groups.

Using Auto-RP, how would you configure the MA to give preference to
one RP over another? You can't filter announcements on the MA, 'cause
then you don't have any redundancy. The MA is going to choose the RP
with the highest IP address. I think this rules out Auto-RP. One
workaround might be to configure multiple 'ip pim send-rp-announce'
commands on the RPs, each referencing different loopback interfaces.

Example:

R1:
!
interface lo0
 ip address 10.10.10.1 255.255.255.255
interface lo1
 ip address 11.11.11.1 255.255.255.255
!
ip pim send-rp-announce lo0 scope 255 group-list GROUP-SET-2
ip pim send-rp-announce lo1 scope 255 group-list GROUP-SET 1
!
ip access-list extended GROUP-SET-1
 permit 224.0.0.0 7.255.255.255
ip access-list extended GROUP-SET-2
 permit 232.0.0.0 7.255.255.255

R2:
!
interface lo0
 ip address 11.11.11.2 255.255.255.255
interface lo1
 ip address 10.10.10.2 255.255.255.255
!
ip pim send-rp-announce lo0 scope 255 group-list GROUP-SET-2
ip pim send-rp-announce lo1 scope 255 group-list GROUP-SET 1
!
ip access-list extended GROUP-SET-1
 permit 224.0.0.0 7.255.255.255
ip access-list extended GROUP-SET-2
 permit 232.0.0.0 7.255.255.255

This essentially uses the "highest IP address wins" rule to indirectly
influence the decision the mapping agent is going to make.

Using Anycast RP, which essentially involves a static RP configuration
on the multicast routers pointing at a single IP address, with R1 and
R2 configured with an MSDP peering and the same IP address on their
respective loopbacks, how are you going to ensure that R1 serves as
the RP for group set 1 and R2 handles group set 2?

Despite being able to meet the requirements using Auto-RP as above
(disclaimer: I haven't tested that), I think using BSR's built-in
priority function is the most elegant solution. Happy to stand
corrected; I'm working through a lot of this stuff at the moment too.

cheers,
Dale

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Received on Tue Apr 14 2009 - 17:28:41 ART