Hi all, Till now, it seem that the only remaining technical reason for some people to prefer VXLAN/NVGRE encapsulation format to MAC-in-MPLS-in-IP encapsulation format for network virtualization overlay is the former has global VNIs while the latter doesn't have. If this reason is true, why can't we consider the possibility of using global MPLS labels to achieve the same goal?
In fact, there are multiple possible ways to achieve global MPLS labels: 1) the first way is to allocate a label block from the existing label space and use it as a global label space from which VPN labels are assigned. In this way, the VPN label of a given VN is set to the corresponding VNI. This approach doesn't require any change to the data plane. 2) the second way is to allocate a separate protocol type code for the global MPLS label so as to distinguish global labels from downstream-assigned and upstream-assigned labels. This approach requires some change to the data plane of PE routers. 3) the third way is to reserve a special purpose label to indicate that the label below such special purpose label is a global label. This approach requires some change to the data plane of PE routers as well. In case 2) and 3), the global label space mentioned above could be a label space dedicated for VNI or a label space which is shared with other applications (e.g., segment routing). Any comments? Best regards, Xiaohu
