Saju Mathew

Cloud December 2, 2021

Multiple Virtual Network Interfaces Maximizing Throughput in IBM Cloud VPC

7 min read - A look at the benefit of using multiple network interfaces in IBM Cloud VPC to obtain network bandwidth beyond the rate limit of a single network interface. In IBM Cloud Virtual Private Cloud (VPC), a user can attach more than…

Cloud October 29, 2021

Multiple Virtual Network Interfaces Connectivity and Usage in IBM Cloud VPC: Part 3

6 min read - In the third part of this three-part series, we will present two advanced approaches to configure routing rules for multiple network interfaces. Source Interface Based Routing Tables involve creating individual routing tables that are specific to each interface. Network Namespaces…

Cloud October 28, 2021

Multiple Virtual Network Interfaces Connectivity and Usage in IBM Cloud VPC: Part 2

3 min read - In the second part of this three-part blog series, we will demonstrate adding custom routing rules to accomplish the separation and then test the reachability. This is one of the simplest methods to achieve reachability in an existing virtual machine…

Cloud October 26, 2021

Multiple Virtual Network Interfaces Connectivity and Usage in IBM Cloud VPC: Part 1

4 min read - Part one of a three-part series investigating a multi-zonal workload utilizing multiple network interfaces and discussing reachability among interfaces. In IBM Cloud, more than one network interface can be attached to a virtual server instance. Having multiple network interfaces allows…

Cloud March 5, 2021

Diagnosing Packet Loss in Linux Network Virtualization Layers: Part 5

4 min read - In this post, we will demonstrate a solution to the concurrency bug described in Part 4 by patching a running kernel. This is the final post of our blog series that is intended for network administrators and developers who are…

Cloud March 3, 2021

Diagnosing Packet Loss in Linux Network Virtualization Layers: Part 4

6 min read - Building on work described in Parts 1, 2, and 3 of this series, we present a careful study of the Linux kernel source code related to macvtap queue handling and the potential for data races there. We will then show…

Cloud February 25, 2021

Diagnosing Packet Loss in Linux Network Virtualization Layers: Part 3

4 min read - In the third part of this five-part series, we will explain how we examined data structures in the Linux kernel to diagnose the packet loss issue described in Part 1. We will show how we used SystemTap to probe the…

Cloud February 24, 2021

Diagnosing Packet Loss in Linux Network Virtualization Layers: Part 2

5 min read - In the second part of this five-part blog series, we will explain the Linux network virtualization layers and introduce a tool called SystemTap. We used SystemTap to narrow down the scope of the packet loss issue described in Part 1.…

Cloud February 23, 2021

Diagnosing Packet Loss in Linux Network Virtualization Layers: Part 1

4 min read - Packet loss is the most common and the most serious issue in networks. Sometimes it takes weeks or even months for network administrators and developers to diagnose packet loss. Diagnosis becomes even more difficult in a cloud infrastructure, where the…