[c-nsp] IP LFA in ring topology

[Adam Vitkovsky]

>load your IGP up with the soft state from multicast; it can be potentially
large, and frequently-changing
>PIM has to deal with the whole register/register-stop and other junk
Right these are relevant arguments of course
But the mcast states doesn't necessarily need to be carried by the same
process as your PE loopbacks 
My point is, that because we don't have mcast routes/states in link state
protocol we can't deploy any reasonable fast reroute technique for mcast
flows

I guess it's all because back in the days the RP cycles where meant to be
used up primarily by ip forwarding and nobody wanted any more complicated
control protocols than the necessary minimum to take up the available cycles

adam
-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Phil Mayers
Sent: Friday, November 30, 2012 11:35 AM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] IP LFA in ring topology

On 11/30/2012 08:46 AM, Adam Vitkovsky wrote:
>> global labels would even allow us to get rid of LDP, by distributing
> labels via ISIS
> And that would be AWESOME, I didn't quite get the idea of creating 
> other RIP like protocols in favor of existing link-state protocols 
> -same goes for PIM vs ISIS

You mean like MOSPF?

Frankly, I don't see why you'd want to load your IGP up with the soft state
from multicast; it can be potentially large, and frequently-changing. I
*like* that PIM runs above the IGP.

Also, PIM has to deal with the whole register/register-stop and other junk.
So it's not just carrying routes.

LDP is of course a slightly different matter. It may indeed have made sense
to put labels in the IGP rather than LDP. But there are things LDP can do
(e.g. multi-hop sessions for PW) that IGP can't. And once you've got LDP for
those, you may as well leave the IGP alone - I guess that was the reasoning.
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