Re: [dpdk-dev] 2.3 Roadmap

[Matthew Hall <mhall@mhcomputing.net>]

On Tue, Dec 01, 2015 at 01:57:39PM +0000, Bruce Richardson wrote:
> Hi Matthew,
> 
> Couple of follow-up questions on this:
> * do you need the exact same number of bits in both implementations? If we support
> 21 bits of data in IPv6 and 24 in IPv4 is that an issue compared to supporting
> 21 bits just in both for compatibility.
> * related to this - how much data are you looking to store in the tables?
> 
> Thanks,
> /Bruce

Let me provide some more detailed high level examples of some security use 
cases so we could consider what makes sense.

1) Spamhaus provides a list of approximately 800 CIDR blocks which are so 
bad that they recommend null-routing them as widely as possible:

https://www.spamhaus.org/drop/
https://www.spamhaus.org/drop/drop.txt
https://www.spamhaus.org/drop/edrop.txt

In the old implementation I couldn't even fit all of those, and doing 
something like this seems to be a must-have feature for security.

2) Team Cymru provides lists of Bogons for IPv4 and IPv6. In IPv4, there are 
3600 bogon CIDR blocks because many things are in-use. But the IPv6 table has 
65000 CIDR blocks, because it is larger, newer, and more sparse.

http://www.team-cymru.org/Services/Bogons/fullbogons-ipv4.txt
http://www.team-cymru.org/Services/Bogons/fullbogons-ipv6.txt

Being able to monitor these would be another must-have for security and is 
quite popular for core routing from what I have heard.

3) At any given time, through various methods, I am aware of around 350,000 to 
2.5 million recent bad IP addresses. Technically single entries could be 
matched using rte_hash. But it is quite common in the security world, to look 
at the number of bad IPs in a class C, and then flag the entire subnet as 
suspect if more than a few bad IPs are present there.

Some support for some level of this is a must-have for security and firewall 
use cases.

4) Of course, it goes without saying that fitting the contents of the entire 
Internet BGP prefix list for IPv4 and IPv6 is a must-have for core routing 
although less needed for security. I am not an expert in this. Some very basic 
statistics I located with a quick search suggest one needs about 600,000 
prefixes (presumably for IPv4). It would help if some router experts could 
clarify it and help me know what the story is for IPv6.

http://www.cidr-report.org/as2.0/#General_Status

5) Considering all of the above, it seems like 22 or 23 unsigned lookup bits 
are required (4194304 or 8388608 entries) if you want comprehensive bad IP 
detection. And probably 21 unsigned bits for basic security support. But that 
would not necessarily leave a whole lot of headroom depending on the details.

Matthew.