In a previous post, I discussed how Maximum Flow problems can be used for network optimization. We focused on a scenario where demands were already routed in the network, and our objective was to determine the maximum demand that could be handled between a given source and a destination metro. We solved this problem by calculating the residual bandwidth for the graph, creating fake demand nodes for each metro with high-capacity edges to avoid them being bottlenecks, and applying Dinic’s algorithm between the source and the destination metro. This is also called a Single Commodity Flow Problem.
We then extended the problem to consider two metros sending traffic to the same destination sink and used the Network Simplex algorithm to determine the maximum traffic the network could accommodate. This is also known as a Multi Commodity Flow Problem. Finally, we validated our findings by routing the results through a network model.
In this post, we will discuss another constraint-based problem called Minimum Maximum Link Utilization (MMLU). The primary goal of MMLU is to route traffic demands in a network to minimize the maximum link utilization. In other words, we aim to distribute the traffic evenly across the network links to Continue reading
Every time someone tries to persuade you to buy (expensive) big-buffer data center switches, take an antidote: the Things we (finally) know about network queues article by Avery Pennarun.
Every time someone tries to persuade you to buy (expensive) big-buffer data center switches, take an antidote: the Things we (finally) know about network queues article by Avery Pennarun.
All Routing Protocol Convergence videos from the How Networks Really Work webinar are now public. Enjoy!
At the start of the year a very interesting (and some would say inevitable) event happened involving internet routing security, the first case study of a large-scale victim o
Most providers will only accept a /24 or shorter IPv4 route because routers have always had limited amounts of forwarding table space. In fact, many hardware and software IPv4 forwarding implementations are optimized for a /24 or shorter prefix length. Justin Wilson joins Tom Ammon and Russ White to discuss why the DFZ might need to be expanded to longer prefix lengths, and the tradeoffs involved in doing so.
Last time, we discussed the first line of defense against fat finger incidents: limiting the number of BGP prefixes your router accepts from a BGP neighbor. However, you can do much more without deploying customer-specific filters (which might require a customer database) or ROV/RPKI.
You can practice the default filters you should always deploy on EBGP sessions with your customers in the Stop the Propagation of Configuration Errors lab exercise.
Last time, we discussed the first line of defense against fat finger incidents: limiting the number of BGP prefixes your router accepts from a BGP neighbor. However, you can do much more without deploying customer-specific filters (which might require a customer database) or ROV/RPKI.
You can practice the default filters you should always deploy on EBGP sessions with your customers in the Stop the Propagation of Configuration Errors lab exercise.