Packet propagation delay reduction is becoming the primary concern of the Internet. Internet service providers (ISPs) attempt to optimize packet routing to offer the best route to their subscribers by achieving desired network performance. Consequently, a route computation metric that uses packet propagation delay instead of link state will be a strong incentive for ISP routing optimization, in which case ISPs could ensure minimal delay route paths for their subscribers. To this end, we present SLRouting, a novel Interior Gateway Routing Protocol. SLRouting calculates a composite route metric using packet waiting delays of servers and routers as well as the packet propagation delay of network links. SLRouting computes the route matrix by selecting the minimal delay path for destination networks. This paper presents the first version of the SLRouting including its theory, design, and implementation notes. A prototype of the proposed protocol is implemented using the ns-3 simulator, and the results were used to evaluate the proposed protocol.