Dear participants, As you may already know, the evaluation phase of the Graph Neural Networking challenge will start soon (Sep. 16). I attach a document with detailed instructions on how to register in the evaluation platform and prepare your submissions. Please, try to register in the platform before the evaluation phase starts (Sep. 16) to avoid potential issues. Also, we recommend to validate the format of your submission files. For this, you can use a toy dataset we provide. Please refer to the attached document for detailed instructions on this. We encourage all of you to participate in the evaluation. Even if you think your solution may not be among the top ones, you may eventually be gladly rewarded and appear in the final ranking we will publish in the challenge website. Also, keep in mind that there are three winning positions, which will have access to the Grand Challenge Finale of the ITU AI/ML in 5G challenge. Please do not hesitate to contact us if you have any problems or questions. Enjoy the challenge! Challenge website: https://bnn.upc.edu/challenge/gnnet2021 Best regards, José Suárez-Varela Postdoctoral Researcher Barcelona Neural Networking center Universitat Politècnica de Catalunya