Flexible Vertex Format Constants in Direct3D 11
Vertex formats are specified in D3D11 using the input layout. An example input layout description for your vertex might look like:

D3D11_INPUT_ELEMENT_DESC aInputDescs[] =
{
    { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, UINT(offsetof(Vertex, p)), D3D11_INPUT_PER_VERTEX_DATA, 0 },
    { "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, UINT(offsetof(Vertex, n)), D3D11_INPUT_PER_VERTEX_DATA, 0 },
    { "UV", 0, DXGI_FORMAT_R32G32_FLOAT, 0, UINT(offsetof(Vertex, tu)), D3D11_INPUT_PER_VERTEX_DATA, 0 },
};