Patent ID: 7007082

Claim:
A system for monitoring packet loss of user packets sent from a user network and addressed for delivery to the user network via a provider network, forward user packets moving in a forward direction from the user network to the provider network and then in a return direction from the provider network to the user network as return user packets, the system comprising: a service level probing box; and a monitoring center in communications with the service level probing box, wherein the service level probing box receives from the user network the forward user packets and outputs the forward user packets to the provider network; wherein the service level probing box further outputs to the provider network loss measuring packets comprising a first loss measuring packet and a second loss measuring packet, each of the loss measuring packets (1) addressed for delivery to the user network via the provider network, (2) including an identifier enabling a receiving portion of the service level probing box to recognize the loss measuring packets as being distinct from the return user packets, and (3) further including an inserted count of the forward user packets and outputted loss measuring packets previously output by the service level probing box to the provider network; wherein the service level probing box outputs the loss measuring packets such that at least one of the forward user packets separates the first and the second loss measuring packets; wherein the service level probing box receives from the provider network the return user packets and the loss measuring packets; wherein the service level probing box examines the return user packets and the received loss measuring packets to separate the received loss measuring packets from the return user packets and extracts from each of the received first and the received second loss measuring packets the inserted count; wherein the service level probing box counts the return user packets and the received loss measuring packets received from the provider network between a time when the service level probing box receives the first loss measuring packet and a time when the service level probing box receives the second loss measuring packet; wherein the service level probing box performs monitoring of packet loss based on the count and each of the inserted counts in the received first and the received second loss measuring packets; wherein the service level probing box sends results of the monitoring to the monitoring center; and wherein the service level probing box outputs to the user network the return user packets but not the received loss measuring packets.