he video delivered to some of participants will be of low quality (since packet losses and/or delays will be high on some branches of the tree). The second case is safest, but it results in disturbing the bulk of the participants. In practice, it is not clear how to choose an adequate value for this fraction. In IVS, we set the fraction to a few percent [2, 3]. Ideally, however, the source should be able to single out the parts of the multicast tree that experience congestion. In order not to disturb the bulk of participants in the tree, these branches should be treated separately. Two possible solutions include video gateways, and using some form of layered coding. Video gateways or layered coding schemes are not new ideas. Our contribution is to identify and discuss the issues associated with using these techniques in the Internet. We illustrate our points with the H.261[10] software coder of IVS. 2 Video gateways Video gateways take