What is the most standard subnet length on internet

Tue Jul 21 06:55:24 UTC 2009

Basically /24s are the longest prefix size accepted by providers unless
you are dealing RTBH (triggered blackholing services). Another
requirement to ensure acceptance of an IP block, especially smaller
assignments are equivalent route objects matching it (in most cases your
provider will do it on your behalf).

/Kana
> Hi all, 
>
> I appreciate many people gave me advices,
> Some of persons asked me about my questions, I'm sorry for that I couldn't reply to everyone.
> Because of your help, I could get many opinions and standards regarding IP allocation policy.
>  
> by the way, in APNIC's IP allocation sizes policy, there is a comments like below.
> "Below are the minimum sizes for allocations and assignments, This information is provided at the request of the ISP community
> to assist in filtering policy decisions "
> Currently, is there any provider filtering routes under LIR's minimum allocation size such as /22 ? 
>
> Best regards,
> =============================================
>  Chi-Young Joung
>  SAMSUNG NETWORKS Inc.
>  Email: lionair at samsung.com
>  Tel +82 70 7015 0623, Mobile +82 17 520 9193
>  Fax +82 70 7016 0031
> =============================================
>
> ------- Original Message -------
> Sender : Danny McPherson<danny at tcb.net> 
> Date   : 2008-12-21 02:42 (GMT+09:00)
> Title  : Re: What is the most standard subnet length on internet
>
>
> On Dec 18, 2008, at 9:43 PM, 정치영 wrote:
>
>   
>> Suresh,
>>
>> Yes, I guess my concern is close to the second meaning.
>>
>> It seems so simple. Currently annoucement of /24 seems to be okey,  
>> most upstream providers accept this.
>> However I wonder if there is any ground rule based on any standard  
>> or official recommandation.
>> If there is some standardized rule about prefix length to be  
>> annouced, I will make my bgp & IP allocation policy of
>> each data center of my company, and I will be able to more fairly  
>> and squarely speak to my customer like this
>> "You have to change your server's IP address if you want move your  
>> server to other place"
>>     
>
> Some useful guidance is provided here (and in
> subsequent references) as well:
>
> An Architecture for IP Address Allocation with CIDR
> <http://tools.ietf.org/html/rfc1518>
>
> Classless Inter-Domain Routing (CIDR): an Address Assignment and  
> Aggregation Strategy
> <http://tools.ietf.org/html/rfc1519>
>
> Network Renumbering Overview
> <http://tools.ietf.org/html/rfc2071>
>
> A Framework for Inter-Domain Route Aggregation
> <http://tools.ietf.org/html/rfc2519>
>
> HTH,
>
> -danny
>
>   