I may not completely understand your concerns, especially about customers moving. I would, however, strongly encouraging not using the terms A,B or C in NANOG discussions; I've found they lead to assumptions based on obsolete ideas. Let's assume an enterprise has had one transit provider, who is in the default-free zone. Working together, the customer and provider agreed the customer needed a /23, and the provider assigns 1.0.0.0/23 as a PA subpart of its own space. 1.0.0.0/8. Using RFC 1998 techniques, for load sharing at four POPs of that same provider, that customer then announces, at each POP, a /25 reflecting the /25 used for machines in the local area of that POP, but also announces the /23. With a single provider, the RFC1998 method applies, and the routes announced are tagged with NO-EXPORT. As long as the enterprise is not multihomed, its more-specifics will be handled properly by provider A's announcement of 1.0.0.0/8? Now, assume that customer gets a single link to a different provider B, whose PI space is 2.0.0.0/8. For multihoming to work, at least two things start to happen. Both providers A and B need to announce 1.0.0.0/23 to the rest of the Internet. If only provider B advertised (2.0.0.0/8, 1.0.0.0/23) to the rest of the internet, all traffic to the enterprise would come through provider B, because it announces a more-specific. For the traffic to work, BOTH A and B have to announce 1.0.0.0/23, so other providers, with full routes, spread load to the two providers. The enterprise can still announce both /23 and /25 to Provider A, with NO-EXPORT on the /25's, because Provider A can make use of the /25 to better manage traffic to its POPs. Administratively, Providers A and B have to agree to Provider B advertising a piece of Provider A's space. Am I answering the question you are asking? Á¤Ä¡¿µ wrote:

"You have to change your server's IP address if you want move your server to other place"

-> It is very natural case, but some customer could think of it will be okey to move if they have C class. but I have different idea. because the border router of that center is annoucing more greater IP block, and if customer move to other center with C class, then I have to newly announce that C class at the border router of other center. and then it is the time my hierachy structure is broken. To prevent this situation, I'm trying to find some standard material every person would understand and accept.

============================================= Chi-Young Joung SAMSUNG NETWORKS Inc. Email: lionair@samsung.com Tel +82 70 7015 0623, Mobile +82 17 520 9193 Fax +82 70 7016 0031 =============================================

------- Original Message ------- Sender : Á¤Ä¡¿µ<lionair@samsung.com> °úÀå/±â¼ú1ÆÀ/»ï¼º³×Æ®¿÷½º Date : 2008-12-19 13:43 (GMT+09:00) Title : Re: Re: What is the most standard subnet length on internet

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"

chiyoung ============================================= Chi-Young Joung SAMSUNG NETWORKS Inc. Email: lionair@samsung.com Tel +82 70 7015 0623, Mobile +82 17 520 9193 Fax +82 70 7016 0031 =============================================

------- Original Message ------- Sender : Suresh Ramasubramanian<ops.lists@gmail.com> Date : 2008-12-19 12:37 (GMT+09:00) Title : Re: What is the most standard subnet length on internet

Chi Young, let me clarify one thing here ..

Do you mean IP allocation as in subnet allocation, swipping in apnic or through a rwhois server etc?

Or do you mean "what is the minimum subnet size I can announce on the internet and have other providers not drop it on the floor"?

srs

On Fri, Dec 19, 2008 at 8:10 AM, Á¤Ä¡¿µ <lionair@samsung.com> wrote:

...

Hi everyone,

I'm going to rebuild IP allocation policy of my company and I am looking for some standard reference for my policy. I have already studied some standard like RFC1518, RIPE181, RFC2050 and I got it is very important to maintain hierachy structure. However, what I am really wondering is what is the most standard subnet length that always can be guaranteed through Internet. less than /24 bit ? I could not find any documents about that, which subnet length is most proper value and pursue internet standard policy ?