If your country is on the above list, you MUST apply for and receive a TRV (Temporary Resident Visa) and you will need a letter of invitation. Please request the letter of invitation (http://www.ietf.org/meetings/70-invite_letter.html) the same day that you pay IETF-70 Registration fee. Please be advised that there is a fee associated with the TRV, for more information about this fee and the payment of it, please visit Paying the Fees.
The application for a TRV (Temporary Resident Visa) includes the following items:
Additional information on travling to Canada can be found at:
Determining Entry & Visa Requirements
and
Information on Visiting Canada