IPv6 internet broken, Verizon route prefix length policy

Tue Oct 13 00:40:36 UTC 2009

Owen,

On Oct 12, 2009, at 5:09 PM, Owen DeLong wrote:
> With IPv6, it probably won't be the ideal 1:1 ratio, but, it will come much closer.  

I wasn't aware people would be doing traffic engineering differently in IPv6 than in IPv4.

> Even if the average drops to 1/2, you're talking about a 70,000 route table today,

How big are IPv6 objects in CAMs again?

> and, likely growth in the 250-300,000 route range over the next 5-10 years.
> CAM will probably scale faster than that.

I've heard differing opinions on this (e.g., router ASICs being both some of the most complicated ASICs ever made and being non-commodity parts hence not necessarily following Moore's Law, pin density in those ASICs reaching a point where you start running into crosstalk problems, cats and dogs living together, mass hysteria, etc).  I'm not a hardware guy so I'll just stare blankly.

> The problematic time scale is that time where we have to support dual stack for a majority of the network.  That's what will
> really stress the CAM as the IPv6 table becomes meaningfully large (but not huge) and the IPv4 table cannot yet be
> retired.

Right.  And when are we planning on retiring IPv4 again?

Interestingly, if you're an ISP and you don't want to redeploy your insanely expensive high end routers with the huge CAMs, you might look to see which prefixes you could drop that would cause the least impact to the majority of your customers.  In this light, filtering the crap out of IPv6 would appear to make business sense.

> I think eventually, we're going to have to look at moving to an ID/Locator split method in the IDR realm.

The big challenge with this is backwards compatibility...

Regards,
-drc