[118194] in North American Network Operators' Group
Re: ISP customer assignments
daemon@ATHENA.MIT.EDU (Scott Morris)
Tue Oct 13 20:37:22 2009
Date: Tue, 13 Oct 2009 20:36:39 -0400
From: Scott Morris <swm@emanon.com>
To: Matthew Petach <mpetach@netflight.com>
In-Reply-To: <63ac96a50910131146p78a2aa32o95069e30ee7e7f46@mail.gmail.com>
Cc: NANOG <nanog@nanog.org>
Reply-To: swm@emanon.com
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
That was the point. :)
Scott
Matthew Petach wrote:
>
>
> On Mon, Oct 12, 2009 at 8:32 PM, Scott Morris <swm@emanon.com
> <mailto:swm@emanon.com>> wrote:
>
> How many addresses do you like on point-to-point circuits?
>
> Scott
>
>
> I allocate a /64, but currently I configure only a /127 subnet on the
> actual interface. That prevents the neighbor table explosion/NS/ND
> traffic flooding challenges that can occur otherwise if you configure
> the link as a /64, and some not-nice person decides to start ping
> sweeping or nmapping the subnet; your router has to send out NS
> messages for every address in the /64 being probed, update the
> neighbor table with the incomplete entry, then flush it out when
> no ND message is seen. On a point-to-point link between
> routers you're never going to run stateless autoconfiguration,
> so there's not much downside to configuring it as a /127.
>
> Still...just in case, I do allocate the whole /64 for the link, so
> that if in the future it turns out that for some reason it really,
> *really* does have to be a /64 configured on it, I can make the
> change just by adjusting masks on each end, rather than
> having to actually renumber the entire network.
>
> *shrug* As always, your mileage will vary, but this has
> worked out well for me so far.
>
> Matt
>
