According to http://symfony.com/doc/current/book/routing.html#required-and-optional-placeholders I should be able to have an optional parameter by setting it's default value in defaults.
This seems not working for me anymore.
I was playing with the symfony standard edition as well as vanilla symfony in version 3.0.2

Tested on annotation as well as a yaml routing:

blog:
   path: /blog/{page}
   defaults:  { _controller: AppBundle:Default:blog, page: 1 }

Running: bin/console router:match /blog/2 I get:

But bin/console router:match /blog/
gives:

[ERROR] None of the routes match the path "/blog/"