After much discussion with many different people, including some at registries, I have modified our filter-list to accept /19s in the 206.0.0.0/8 block. The change will take effect upon the next clearing of exterior BGP sessions with our various neighbours. Note that there will be no further relaxtion of the /19 limit, and that the principal reasoning behind the change from /18 to /19 for this block is as follows: -- a miscommunication between me and various registries several months ago which led to registries and perhaps some providers handing out some /19s that they honesty expected would pass through the filters; the fact that they did, to some extent, due to the minor implementation glitch on this side, exacerbated the problem. -- several people have aggregated long prefixes into /19s (thank you) and find that they cannot reasonably do further aggregation to /18s due to various allocation policies. This change increases the number of prefixes AS1239 will route towards by 129, all of which are /19s, and many of which can and should be aggregated into even shorter prefixes. Note that this will not help anyone who is announcing anything longer than a 19-bit prefix in the 206.0.0.0/8 range, nor anyone who is expecting to be able to announce /19s in 207.0.0.0/8 - 239.0.0.0/8. At this time, I don't intend to have AS1239 routers accept /19s in those blocks from its external peers, nor do I expect to increase the maximum length of the prefixes accepted from 206.0.0.0/8 beyond that which registries were allocating as part of their slow-start scheme with the expectation that /19s probably were short enough that they would stay routable everywhere. Sean. - -- Sean Doran <smd@sprint.net>
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Sean Doran