Loop-Free Forwarding Table Updates with Minimal Link Overflow

Abstract

Abstract-The forwarding paths in an IP network may change due to a link failure, network equipment maintenance, or reconfiguration of link weights. The forwarding tables in the routers need then to be updated. These updates may cause transient loops and link overflow, if they are not performed in an appropriate order. While existing proposals achieve loopfree updates, transient link overflow is still a problem during the updating process. In this paper, we present a method that compares the initial and final forwarding paths, and obtains the updatable nodes that do not cause any transient loop or link overflow. However, this goal is not always achievable, therefore, we propose an algorithm to update the forwarding tables that will refrain the link overflows to a minimal level. The performance study on a real topology with two setups confirms that our approach achieves smaller link overflow than by using a previously proposed approach.

Loop-free convergence using ordered FIB updates: Analysis and routing optimization

“…Link utilizations during OFIB are not considered in these papers. Fu, Shi et al [10], [11] address the problem of temporary load increase during the loop-free convergence phase. They propose to tackle this issue by calculating special update orders that reduce the load increase.…”

Leveraging software-defined networking for security policy enforcement

“…27 Given above benefits, many companies, such as Google [8,16] and VMware [31], have used SDN in their data centers. It is 28 also broadly recognized that SDN will be widely deployed in data centers in the near future [12,17]. Therefore, in this paper, we 29 focus on SDN based security policy enforcement.…”

When the cure is worse than the disease: The impact of graceful IGP operations on BGP

“…François et al propose protocol extensions to avoid transient forwarding loops after a link addition or removal [13]. Fu et al [14] and Shi et al [15] generalize these results by defining loop-free reconfiguration techniques encompassing any change in the forwarding plane and considering traffic congestion, respectively. In [16], Vanbever et al propose techniques and tools to safely reconfigure IGP when routers can run two IGP processes simultaneously.…”

“…We can roughly divide those techniques in two approaches. The first approach [22], [14], [15], [23], [12] consists in progressively changing routers' forwarding tables in such a way to minimize or avoid disruptions.The second approach consists in running two control-planes in parallel and applying a convenient operational ordering to switch from one control-plane to the other [10], [16]. In the following, we consider the metric-increment [22] and the ships-in-thenight (SITN) [16] techniques as representatives of the two approaches, respectively.…”