[AusNOG] Whats peoples BCP for Unused IP Space on Routers ?

[David Hughes]

Null route all your aggregates (i.e. the /24 not the unused /25 in this example).  The allocated subnets will be more specific and will work as expected.  Anything else in those blocks will be null routed.


David
...

On 03/12/2012, at 9:55 AM, Shaun Deans wrote:

> Morning Noggers ?
> 
> I'm looking for some quick feedback on what peoples BCP (Best Common
> Practice) is when it comes to unused ip space. For example if you have
> the ip range 1.2.3.0/24 and you only have 1.2.3.0/25 active/routed
> what do you do with 1.2.3.128/25.
> 
> I have seen many techniques including:
> - ACLs (Bad IMHO as it requires CPU cycles)
> - Tying to a Loopback (Bad: Leaves ip's open on router which require acls/cpu)
> - Null routing ( would be my pick)
> - Nothing at all (Very Bad as it would bubble up causing routing loops)
> 
> Gave it a google and there were no real BCP's that stood out so im
> interested to hear what everyone else does ?
> 
> Cheers
> 
> S
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