All, As you may be aware, the DNS root zone will be updated on Monday, February 4, with AAAA resource records for six of the root servers. (Please see http://iana.org/reports/root-aaaa-announcement.html for IANA's official announcement.) In preparation for this change, we have noticed that some sites seem to be having reachability problems to the new root server IPv6 addresses that are located in critical infrastructure Micro-allocations (/47s or /48s), but not to the root servers located in /32s. Further testing has shown that we can ping these sites experiencing reachability problems when sourcing the provider allocated (PA) space on our links that aggregates up to a /32, but not when sourcing from the provider independent (PI) /48s of our root servers. With the AAAA RRs going into the root zone on Monday, now is a good time to check your IPv6 route filters. To prevent reachability problems, network operators should update IPv6 route filters to permit up to at least /48s from the appropriate RIR Micro-allocation blocks. I tried to gather as many of these blocks as I could find from the RIRs. Notably, I wasn't able to identify anything from AfriNIC -- hopefully someone on the list will be able to fill in that gap. This list is not meant to be complete nor authoritative, but it does cover all of the root server IPv6 addresses that are going live on Monday (that we are aware of) and that are in blocks allocated as /47s or 48s. That being said, please accept at least /48s from these blocks ASAP, or your network may experience reachability problems to the IPv6 root servers. ARIN (http://www.arin.net/reference/micro_allocations.html, http://www.arin.net/policy/nrpm.html#six10) 2001:0500::/30 RIPE (https://www.ripe.net/ripe/docs/ripe-ncc-managed-address-space.html) 2001:7F8::/29 APNIC (http://www.apnic.net/db/min-alloc.html) 2001:0C00:/23 2001:07FA:/32 LACNIC (http://lacnic.net/en/registro/index.html) 2001:12f8:0000::/35 2001:12f8:4000::/35 If you are having IPv6 reachability problems to the V6 IP addresses for a.root-servers.net and j.root-servers.net (2001:503:BA3e::2:30 and 2001:503:C27::2:30) please feel free to contact us. We may be able to assist in getting filters updated or working around any connectivity issues. Thank you, Frank Scalzo VeriSign