IPv6 internet broken, Verizon route prefix length policy

Tue Oct 13 00:09:41 UTC 2009

On Oct 12, 2009, at 4:37 PM, David Conrad wrote:

> Mark,
>
> On Oct 12, 2009, at 3:40 PM, Mark Andrews wrote:
>>> Verizon's policy has been related to me that they will not accept or
>>> propogate any IPv6 route advertisements with prefix lengths longer  
>>> than
>>> /32.  Full stop.  So that even includes those of us that have /48 PI
>>> space from ARIN that are direct customers of Verizon.
>>
>> Looks like Verizon doesn't want any IPv6 customers.  If a company
>> has idiotic policies like this vote with your wallet.
>
> Not knowing all the details, it is difficult for me to judge,  
> however it is worth observing that provider independent addresses,  
> regardless of where they come from or whether they are IPv4 or IPv6  
> simply do not scale.  In the face of everybody and their mother now  
> being able to obtain PI prefixes from all the RIRs, any ISP that  
> handles full routing is going to have to hope their router vendor of  
> choice can keep buying more/bigger CAMs (passing the expense on to  
> the ISP who will pass it on to their customers) and/or they'll start  
> implementing the same sort of prefix length limitations that we saw  
> back in the mid-90s.
>
I disagree.  With IPv4 the bigger issue is that everyone and their mom  
has 9 different announcements behind their single ASN.

With IPv6, it probably won't be the ideal 1:1 ratio, but, it will come  
much closer.  Even if the average drops to 1/2, you're
talking about a 70,000 route table today, and, likely growth in the  
250-300,000 route range over the next 5-10 years.
CAM will probably scale faster than that.

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.

> And, of course, we have IPv4 runout in the near future with the  
> inevitable market which will almost certainly promote the use of  
> longer prefixes.
>
There is that problem, too.  Personally, I think the market was a  
horrible idea, but, it had way too much momentum for
me to be able to stop it.

> In other words, get used to it.
>
Pretty much.  I think eventually, we're going to have to look at  
moving to an ID/Locator split method
in the IDR realm.

Owen