Re: Is a /48 still the smallest thing you can route independently?
--- jrhett@netconsonance.com wrote: From: Jo Rhett <jrhett@netconsonance.com> I've finally convinced $DAYJOB to deploy IPv6. Justification for the IP space is easy, however the truth is that a /64 is more than we need in all locations. However the last I heard was that you can't effectively announce anything smaller than a /48. Is this still true? Is this likely to change in the immediate future, or do I need to ask for a /44? ---------------------------------------------------- A /48 is 65536 /64s and a /44 is 16x65536 /64s. If you only need one subnet (1 subnet = 1 /64), why would you try to get 16x65536 subnets, rather than the 65536 you have in the /48? scott
--- jrhett@netconsonance.com wrote: From: Jo Rhett <jrhett@netconsonance.com>
I've finally convinced $DAYJOB to deploy IPv6. Justification for the IP space is easy, however the truth is that a /64 is more than we need in all locations. However the last I heard was that you can't effectively announce anything smaller than a /48. Is this still true?
Is this likely to change in the immediate future, or do I need to ask for a /44? ----------------------------------------------------
A /48 is 65536 /64s and a /44 is 16x65536 /64s. If you only need one subnet (1 subnet = 1 /64), why would you try to get 16x65536 subnets, rather than the 65536 you have in the /48?
scott
He said it was for multiple sites. Per ARIN policy, the next biggest chunk from a /48 is a /44, so a /44 is what should be asked for. It is perfectly justifiable if you have more than 1 site. I would not expect anything smaller than a /48 to be allowed in BGP. A bonus would be that a /44 currently costs the same as a /48 for an enduser, so there really is no drawback from getting the /44, and having enough space to not have to worry about it in the future. -Randy
On Oct 11, 2012, at 2:28 PM, Randy Carpenter wrote:
so there really is no drawback from getting the /44, and having enough space to not have to worry about it in the future.
It's only a worry if you can only route /48s, which was my question. And seriously, we're going to be banging around in the emptiness as compared to our IPv4 allocations. :) -- Jo Rhett Net Consonance : net philanthropy to improve open source and internet projects.
----- Original Message -----
On Oct 11, 2012, at 2:28 PM, Randy Carpenter wrote:
so there really is no drawback from getting the /44, and having enough space to not have to worry about it in the future.
It's only a worry if you can only route /48s, which was my question. And seriously, we're going to be banging around in the emptiness as compared to our IPv4 allocations. :)
You can route /48 or shorter (larger) How many sites do you have? If less than 192, /44 is perfect, unless some of those sites require more than a /48. Then, it gets more complicated :-) -Randy
On Thu, 11 Oct 2012, Randy Carpenter wrote:
You can route /48 or shorter (larger)
How many sites do you have? If less than 192, /44 is perfect, unless some of those sites require more than a /48. Then, it gets more complicated :-)
A /44 would give you 16 /48s. If you have 192 sites - assuming a /48 per site - you would want at least a /40. jms
On Thu, Oct 11, 2012 at 6:06 PM, Randy Carpenter <rcarpen@network1.net> wrote:
How many sites do you have? If less than 192, /44 is perfect, unless some of those sites require more than a /48. Then, it gets more complicated :-)
We're having a general math breakdown today. First Jeroen wants to fit 5 /48's in a /47 and now you want to fit 192 /48's in a /44. 48-44=4. 2^4=16. -Bill -- William D. Herrin ................ herrin@dirtside.com bill@herrin.us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004
Wow and I thought nibble boundaries would make the math easier than HD ratios. Here's the breakdown for those who are mathematically challenged: n sites prefix 0 Nothing. 1 /48 2-12 /44 13-191 /40 192-3071 /36 3072-49,151 /32 49,152-786,431 /28 If you're managing more than 786,431 sites, then you should be able to afford to hire someone who can properly handle the math. Owen
----- Original Message -----
On Thu, Oct 11, 2012 at 6:06 PM, Randy Carpenter <rcarpen@network1.net> wrote:
How many sites do you have? If less than 192, /44 is perfect, unless some of those sites require more than a /48. Then, it gets more complicated :-)
We're having a general math breakdown today. First Jeroen wants to fit 5 /48's in a /47 and now you want to fit 192 /48's in a /44.
48-44=4. 2^4=16.
-Bill
Yep... I don't know why, but I was thinking /40. So, 1 site = /48 2-12 sites = /44 13-192 sites = /40, and so on. NRPM 6.5.8.2 for details. /40 bumps you into the next price category, but it is a 1-time expense for endusers. -Randy
On 10/11/12, William Herrin <bill@herrin.us> wrote:
On Thu, Oct 11, 2012 at 6:06 PM, Randy Carpenter <rcarpen@network1.net> wrote: >> How many sites do you have? If less than 192, /44 is
perfect, unless some of those sites require more than a /48. Then, it gets more complicated :-)
We're having a general math breakdown today. First Jeroen wants to fit 5 /48's in a /47 and now you want to fit 192 /48's in a /44. 48-44=4. 2^4=16.
Right, last I checked the smallest integer >= Log base 2 of 5 is not less than or equal to 1, therefore, you will never fit 5 /48s in the network just by subtracting 1 from the prefix length. if you want a prefix /yy that will accommodate a certain number N of /xx Then you must ensure that 2^(xx - yy) >= N not 5^(xx -yy ) >= N
-Bill
-- -J
participants (7)
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Jimmy Hess -
Jo Rhett -
Justin M. Streiner -
Owen DeLong -
Randy Carpenter -
Scott Weeks -
William Herrin