Real-Time and Consistent Route Update Based on Segment Routing for NFV-enabled Networks

Abstract

In NFV-enabled networks, it is necessary to frequently update the flow’s route to ensure that the network continues performing well due to flow dynamics. In previous SFC route update schemes, the optimization goal mainly focused on the load balance of the network (e.g., VNF and link) and seldom paid attention to the update delay. Therefore, these schemes either take a too long time or have very high rule-space costs; they can’t be used in a large or frequently changed network. When we update the SFC route, we face two challenges: real-time update and path consistency guarantee. Specifically, most flows have a short duration, so route updates that take a too long time will make the new route unsuitable for the current network’s workload. Path consistency requires that only one route configuration is used for packets in the update process. Otherwise, in-flight packets might meet with forwarding errors (e.g., loops). In this paper, we propose to use segment routing technology to deal with the problem of path inconsistent. We formalize the real-time SFC route update problem (RSRU) by jointly optimizing the update delay and the load of VNF. Then we design an algorithm called RBRU based on randomized rounding to solve it with a bounded approximate ratio. The simulation results show that RBRU can reduce the update delay by 41.3%–57.9% compared with the comparison algorithms when achieving a similar VNF load balancing effect.