[c-nsp] Symmetrical Routing

[Pavel Vraštiak]

I am looking into uRPF now - is it true for all platforms that, with 
uRPF enabled, packets must be received on the best path only? Is there 
any list of platforms that can handle multipath? Can some hande 
unequal-cost-MP?

Notes like this are a little confusing for me:
The behavior of strict RPF varies slightly by platform, number of 
recursion levels, and number of paths in Equal-Cost Multipath (ECMP) 
scenarios. A platform may switch to loose RPF check for some or all 
prefixes, even though strict RPF is configured.

Best regards
pV

On 03/21/2013 11:05 PM, Nick Hilliard wrote:
> On 21/03/2013 09:41, M K wrote:
>> Hi I have many international links active and each link is exported with
>> certain prefixMy question is should the outbound traffic go through the
>> same link as well , symmetrical ? or it's not an issue to have the
>> export from a link and the import for the same prefix from another one
>> ?
> it depends on your upstream configuration.  If they have strict urpf
> enabled, then asymmetric routing will be a problem.  If they don't, then it
> should be fine.  Your router is not a firewall, so it doesn't care about
> receiving packets on the "wrong" interface unless you tell it to via urpf /
> acls.
>
> Nick
>
>
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