There's a mandate that backbones be dual stack. Basically nobody pays attention to it. https://georgewbush-whitehouse.archives.gov/omb/memoranda/fy2005/m05-22.

There's a mandate that backbones be dual stack. Basically nobody pays attention to it. https://georgewbush-whitehouse.archives.gov/omb/memoranda/fy2005/m05-22.pdf https://georgewbush-whitehouse.archives.gov/omb/memoranda/fy...