<nav>
  <ul>
    <li><a routerLinkActive="active" routerLink="./details">Details</a></li>
    <li><a routerLinkActive="active" routerLink="./activity">Activity</a></li>
  </ul>
</nav>

<a routerLinkActive="active" routerLink="./">Details</a>

const routes: Routes = [
  { path: 'users', loadChildren: 'app/users/users.module#UsersModule' }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

const routes: Routes = [
  { path: '', component: UserListComponent },
  { path: 'profile/:id', component: ProfileComponent,
    children: [
      { path: 'details', component: ProfileDetailsComponent },
      { path: 'activity', component: ProfileActivityComponent },
      { path: '**', redirectTo: 'details'}
    ]
  }
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule]
})
export class UsersRoutingModule { }