From a routing table perspective there is no difference if the prefix is longer or shorter. When asking around which prefix length would have a good chance to ensure the goal of not beeing filtered I have felt consensus
Dear WG! I have followed the discussion about the TLD Anycast Allocation Policy and decided not to quote from the previous posting but to pick up the arguments - as I have understood them - and pointing to the places where I have tried to address them in my policy draft. 1. Is there a need for anycasting at all ? I was surprised to see this question on the list. I think that anycasted nameservers are an accepted standard and there is no need to discuss pros and cons anymore. 2. /32 vs. /48 V6 prefix - routability aspect that a /32 has by far the best chances. However I'm considering if it wouldn't be best to declare a /32 microallocation block from which RIPE will assign /48 blocks. 3. /32 vs. /48 V6 prefix - address conservation aspect There is no question that a /32 is quite a big block and that this sacrifice to "ensure" reachability from most network places is worth it. This question should be raised at regular intervals which is covered by renewing/adjusting/withdrawing the policy if circumstances have changed. I felt that there has been consensus within the folks I have talked to that a /32 is currently a good thing to keep the komplexity of anycast deployment at a bearable level. However the last disccusion showed me that a lot of people would prefer to assign /48 from a /32 TLD Anycast Allocation Block. 4. Are the number of assignments under this policy limited? The policy in its current form implies a limit of one V4 and one V6 block assignment because as soon as one assigment is made there is no chance to pass the referenced IANA test to get another assignment. 5. Who gets the address assignment? The assignment is bound to a TLD nameservice. Therefore the applicant would be a TLD administrator. The TLD administrator can use this assignment either by himself or hand it to an anycast provider that will operate the anycast nameservers for him. I don't think that sharing an assignment between multiple TLDs if they outsource their operation to an anycasting DNS provider should be a must to separate TLD operations from each other and that the extra address space spent is a good thing keeping in mind the limited number of TLDs where talking about. Summary: I hope with my explanation it explains that most of the concerns have been addressed already. Allocating a /32 prefix to all RIPE TLD anycast assignments should help to address concerns about address space usage and make setting up routing filters easier. Any comments or suggestions? Andreas -- DENIC e.G. Phone :+49 69 27235 120 Wiesenhuettenplatz 26 Fax :+49 69 27235 235 D-60329 Frankfurt Mail : baess@denic.de -- DENIC e.G. Phone :+49 69 27235 120 Wiesenhuettenplatz 26 Fax :+49 69 27235 235 D-60329 Frankfurt Mail : baess@denic.de