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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: BGP Question - how do work around pigheaded ISPs
On Fri, Feb 09, 2001 at 07:35:31PM -0800, Roisman, Dani wrote: ==>- The Premis: ==>A parent organization has an unused /16 of address space, for arguments ==>sake, let's say it's 172.16.0.0/16. It's out of the old "class B" address ==>range. Two groups within the organization want to bring up independant ==>Internet datacenters, and need /18 of address space, each. Since the parent ==>organization owns an unsed /16, the IP registry refuses to give the child ==>organizations any address space - they insist all address blocks assigned to ==>the parent organization be used, first. This is a frequent problem for those who have had address space from some of the older blocks and are trying to go back and better handle. You don't have to allude to who these ISP's are, they publically state their policies. Typically, for these ISP's, one premise is that filtering based on the minimum prefix size that the registry allocated in that particular /8 shields them from legal challenges related to having any sort of filtering policies in the first place. IMO, it just makes the liability greater. After all, what's the difference between 171.16.0.0/19, 171.16.32.0/19 and 64.255.0.0/19, 64.255.32.0/19, as long as the companies who are announcing the blocks are doing so responsibly and for good reason? Why should the first set be filtered but the second not? The next answer that you'll receive are "some of the older companies don't know how to responsibly announce their address space", because some do announce them as /24's. I think that a responsible policy which limits the announcements in the old B space to the minimum allocation ARIN is currently utilizing, or even /19, is perfectly sufficient. It keeps routing tables under control and protects against the infamous UUnet de-aggregation disaster or bad announcements with lengths longer than, say, /20. Yet another off-the-wall answer you'll get is that some ISP's have taken it into their own hands to stop announcements longer than /16's because some old companies might want to sell portions of their /16's to make money. With all the dot-coms closing, I think I'd be more worried about 209+ and 62/63/64... =) And finally, there's always the "there might be a chance someone will pay us to amend our filters for their slot" argument. /cah
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