An Experimental Investigation of Hyperbolic Routing with a Smart Forwarding Plane in NDN

Routing in NDN networks must scale in terms of forwarding table size and routing protocol overhead. Hyperbolic routing (HR) presents a potential solution to address the routing scalability problem, because it does not use traditional forwarding tables or exchange routing updates upon changes in network topologies. Although HR has the drawbacks of producing sub-optimal routes or local minima for some destinations, these issues can be mitigated by NDN's intelligent data forwarding plane. However, HR's viability still depends on both the quality of the routes HR provides and the overhead incurred at the forwarding plane due to HR's sub-optimal behavior. We designed a new forwarding strategy called Adaptive Smoothed RTT-based Forwarding (ASF) to mitigate HR's sub-optimal path selection. This paper describes our experimental investigation into the packet delivery delay and overhead under HR as compared with Named-Data Link State Routing (NLSR), which calculates shortest paths. We run emulation experiments using various topologies with different failure scenarios, probing intervals, and maximum number of next hops for a name prefix. Our results show that HR's delay stretch has a median close to 1 and a 95th-percentile around or below 2, which does not grow with the network size. HR's message overhead in dynamic topologies is nearly independent of the network size, while NLSR's overhead grows polynomially at least. These results suggest that HR offers a more scalable routing solution with little impact on the optimality of routing paths

Convergence

Today’s Internet uses a path vector routing protocol, BGP, for global routing. After a connectivity change, a path vector protocol tends to explore a potentially large number of alternative paths before converging on new stable paths. Several techniques for improving path vector convergence have been proposed, however there has been no comparative analysis to judge the relative merit of each approach. In this paper we develop a novel analytical framework for analyzing the convergence delay bounds of path-vector routing protocols in general. Our framework can accommodate different message processing delay models. By incorporating the commonly used uniform processing delay model we are able to fill in all the cases where analytical results are missing previously. The results obtained by using our framework not only confirm the previous work but also provide new insights into the underlying network behavior. We then present a new delay model, the   model, which takes into account the actual message queueing delay in actual BGP implementations and simulations. By incorporating the   model in our framework, we are able to obtain tighter delay bounds and explain simulation results that cannot be explained using the previous uniform message delay model

Destination reachability and BGP convergence time

Abstract — One important performance measure for routing protocols is packet delivery. An ideal routing protocol should quickly adapt to topological changes and deliver packets as long as any path to the destination exists. In this paper, we examine the packet delivery performance in a network running the BGP routing protocol when a destination may be disconnected from time to time. We develop two metrics, extra downtime and false uptime, to capture the time difference between actual loss of connectivity and perceived unreachability. Our results show that extra downtime closely matches Tup convergence delay, and false uptime closely matches Tdown convergence delay. Furthermore, our results show that, for transient connectivity failures, a shorter Tdown convergence time can have negative impact on packet delivery. I

Bgp dynamics during route flap damping

The BGP routing protocol uses a mechanism called Route Flap Damping [13] to limit the impact of connectivity instability to any individual sites. Although it is believed that this damping mechanism contributes to the stability of global Internet routing, the exact effects of damping has not been thoroughly examined in a large scale network setting. Previous work [8] has shown that damping can be falsely triggered by BGP’s path exploration and significantly extends the routing convergence time after even a single route flap. In this paper we examine the impact of damping under a range of connectivity flapping patterns and different damping parameters. Our results show that damping can confine global routing dynamics to follow a predictable analytical model when connectivity to a destination flaps persistently. However when the number of flaps is small, the global routing behavior deviates from the intended analytical model and damping leads to higher dynamics as measured by both message overhead and network convergence. Such dynamics are largely shaped by the interaction between route reuse timers at different routers; route suppression and reuse at one router can affect the number of routing updates received by other routers, and in turn, others ’ damping behavior. We show how this reuse timer interaction, when combined with BGP path exploration, can lead to a staged behavior of routing updates consisting of charging, suppression, releasing, and possible additional rounds of secondary charging phases. We also examine the effects of flapping interval, damping parameters, and network topology on both message overhead and network convergence. I

CDN Request Routing to Reduce Network Access Cost

Abstract—Content Delivery Networks (CDN) are overlay network of servers being used to deliver growing traffic demands on the Internet. As a result, CDNs are facing ever-increasing operating costs. Internet Service Providers (ISP) charge CDNs on server traffic, computed using common usage-based charging models, e.g. 95th Percentile charging. We propose Network Cost Aware Request Routing, NetReq, that assign user requests to reduce server charging volume. We compare NetReq against nearestavailable server request routing in large scale simulations for both web and multicast traffic requests. NetReq reduces charging volume for both traffic request types, thereby reducing cost. NetReq provides comparable network performance for multicast traffic by introducing end-to-end delay as a constraint in the requestrouting. NetReq marginally increases network performance for web traffic, when content maybe available at every server