[c-nsp] is RPF strict mode common?

[Adam Greene]

Thanks much for the replies on and off list. It does seem like strict RFP 
should *not* be an issue in the way I had been imagining.

Thanks guys!

----- Original Message ----- 
From: "Justin M. Streiner" <streiner at cluebyfour.org>
To: "Adam Greene" <maillist at webjogger.net>
Cc: <cisco-nsp at puck.nether.net>
Sent: Thursday, May 08, 2008 9:42 AM
Subject: Re: [c-nsp] is RPF strict mode common?


> On Thu, 8 May 2008, Adam Greene wrote:
>
>> The obvious solution to me will be to prepend my route announcements to 
>> Global Crossing. However, one question: there is a good chance that some 
>> of my traffic will flow out through Savvis and in through Global Crossing 
>> (in fact, that's almost certainly happening right now). Will this kind of 
>> asymmetrical traffic run into issues with other ISPs that deploy RPF in 
>> strict mode? Are there many ISPs out there that do this?
>
> While it's certainly a plausible scenario, an ISP that runs strict RPF on 
> multihomed customer links is begging for trouble for exactly the reasons 
> you described.  The might run loose RPF, or straight ingress/egress 
> filtering, which should be OK.  Strict RPF is meant for singlehomed sites.
>
> Bottom line, you should be able to alter your edge routing policies in the 
> ways you described to make better utilization of your transit links 
> without too much fear of breaking things in interesting ways...
>
> jms
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