Mechanisms that Enforce Bounds on Packet Lifetimes

Abstract

For reliable transport protocol operation the lifetime of packets should not exceed an assumed maximum packet lifetime (MPL). A packet's Lifetime is spent in nodes and crossing links and subnetworks. Time spent in nodes and on some links and subnetworks is easily found. Other links and subnetworks may lose, duplicate, delay, and reorder data and not provide transit time information. We present a link-transit-time protocol for bounding the transit time of packets that cross such links and subnetworks. The protocol does not require synchronized clocks. In the protocol a receiving node R occasionally sends the value of its clock reliably to a sending node S, which initializes a software send-timer. Node S uses the send-timer to timestamp packets that are sent to node R. Node R can then overestimate each packet's link or subnetwork transit time. © 1983, ACM. All rights reserved.