Traffic measurement is a critical component for the control and engineering of communication networks. We argue that traffic measurement should make it possible to obtain the spatial flow of traffic through the domain, i.e., the paths followed by packets between any ingress and egress point of the domain. Most resource allocation and capacity planning tasks can benefit from such information. Also, traffic measurements should be obtained without a routing model and without knowledge of network state. This allows the traffic measurement process to be resilient to network failures and state uncertainty. We propose a method that allows the direct inference of traffic flows through a domain by observing the trajectories of a subset of all packets traversing the network. The key advantages of the method are that (i) it does not rely on routing state, (ii) its implementation cost is small, and (iii) the measurement reporting traffic is modest and can be controlled precisely. The key idea of the method is to sample packets based on a hash function computed over the packet content. Using the same hash function will yield the same sample set of packets in the entire domain, and enables us to reconstruct packet trajectories. I.

Recently MPLS is used for building up VPNs in IP backbone, called MPLS VPNs. In this paper, we discuss issues on finding routes with QoS requirements (i.e., QoS routing) in MPLS VPNs. We first present background on MPLS VPNs as well as QoS routing. Then we discuss both the benefits and problems resulted from introducing QoS routing into MPLS VPNs. We particularly present an architecture of MPLS VPNs with QoS routing capability, on which we discuss some important issues on running QoS routing in MPLS VPNs.