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: lion...@samsung.com > Tel +82 70 7015 0623, Mobile +82 17 520 9193 > Fax +82 70 7016 0031 > ============================================= > > ------- Original Message ------- > Sender : Á¤Ä¡¿µ<lion...@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: lion...@samsung.com > Tel +82 70 7015 0623, Mobile +82 17 520 9193 > Fax +82 70 7016 0031 > ============================================= > > ------- Original Message ------- > Sender : Suresh Ramasubramanian<ops.li...@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 <lion...@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 ? >> > > > > >
