RIPE IPv6 Folks: Philip Matthews and I are co-authors on an active draft within the IETF related to IPv6 routing design choices. To ensure we are gathering sufficient data we are looking for an expanded set of input from operator forums as well (vs. just the v6ops IETF list). The draft is found here -(https://tools.ietf.org/html/draft-ietf-v6ops-design-choices). We are looking for information on the IGP combinations people are running in their dual-stack networks. We are gathering this information so we can document in our draft which IGP choices are known to work well (i.e., people actually run this combination in production networks without issues). The draft will not name names, but just discuss things in aggregate: for example, "there are 3 large and 2 small production networks that run OSPF for IPv4 and IS-IS for IPv6, thus that combination is judged to work well". If you have a production dual-stack network, then we would like to know which IGP you use to route IPv4 and which you use to route IPv6. We would also like to know roughly how many routers are running this combination. Feel free to share any successes or concerns with the combination as well. We are looking particularly at combinations of the following IGPs: IS-IS, OSPFv2, OSPFv3, EIGRP. If you run something else (RIP?) then we would also like to hear about this, though we will likely document these differently. [We suspect you run RIP/RIPng only at the edge for special situations, but feel free to correct us]. And if you have one of those modern networks that carries dual-stack customer traffic in a L3VPN or similar and thus don’t need a dual-stacked core, then please email us and brag ... If you are on multiple lists at RIPE, NANOG or the IETF, we apologize for any redundant emails you may get (we are just attempting to reach the widest audience possible). Philip Matthews Victor Kuarsingh