Re: [pim] anycast-rp with pim (rfc4610) when an RP reboots

["Prashant Jhingran (pjhingra)" <pjhingra at cisco.com>]

Hi Pekka/All,

- As long as RP_2 remains down there would not be an issue
- However once RP_2 becomes operational then with the help of NULL
Registers (default every 60 sec or so), the black hole should get
patched up in < 2 mins
- Also note that black hole would be created for only new/upcoming
receivers i.e. those behind RP_2 during this transient time
- Recv behind RP_2 which would have ideally switched to SG would remain
unaffected. 

Thus perhaps we need not worry about this scenario. 

 
Regards,
Prashant Jhingran

 
-----Original Message-----
From: pim-bounces at ietf.org [mailto:pim-bounces at ietf.org] On Behalf Of
pavan_kurapati
Sent: Wednesday, October 14, 2009 2:38 PM
To: Pekka Savola
Cc: Srimanikandan Ganesan; pim at ietf.org
Subject: Re: [pim] anycast-rp with pim (rfc4610) when an RP reboots

>   - fom the PIM spec, I don't see the suggested interval between null 
> registers and whether those are mandatory.

RFC suggests register stop timer to be 

The Register-Stop Timer is set to a random value chosen
        uniformly from the interval ( 0.5 * Register_Suppression_Time,
        1.5 * Register_Suppression_Time) minus Register_Probe_Time.

Since the default of Register_Suppression_Time is 60 seconds, a
Null-Register will be triggered <1.5 mins time unless the default values
are changed

Yes, I agree though that things will be up and running in the tune of
1-2 mins time frame which may be significant. 

Thanks,
Pavan

> -----Original Message-----
> From: Pekka Savola [mailto:pekkas at netcore.fi]
> Sent: Wednesday, October 14, 2009 2:17 PM
> To: pavan_kurapati
> Cc: Srimanikandan Ganesan; pim at ietf.org
> Subject: Re: [pim] anycast-rp with pim (rfc4610) when an RP reboots
> 
> On Wed, 14 Oct 2009, pavan_kurapati wrote:
> > Wouldn't the problem be solved when a Null register is triggered 
> > from the DR of RP1?
> >
> >   o If Null Registers are sent (Registers with an IP header and no
IP
> >     payload), they MUST be replicated to all of the RPs in the
> >     Anycast-RP set so that source state remains alive for active
> >     sources.
> 
> Yes -- but:
> 
>   - this helps only until the next null register is received
>   - fom the PIM spec, I don't see the suggested interval between null 
> registers and whether those are mandatory.
> 
> I was not arguing that the blackhole situation would last forever, but

> that it could be significant (let's say, in the order of 3-4 minutes).
> 
> --
> Pekka Savola                 "You each name yourselves king, yet the
> Netcore Oy                    kingdom bleeds."
> Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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