In an earlier blog, I have talked about Linux bridge based virtual networking. Recently as part of a comment on my blog, I learnt how to view and interpret the MAC table of Linux bridge. In this installment of WILT (What I Learnt Today) series, I will share how MAC Table can be used for troubleshooting Linux bridges.
In the next installment of “What I learnt today” or WILT, I briefly touch upon Network Namespace. I came across Namespace as part of my ongoing study of OpenStack networking. Namespaces are powerful constructs in Linux that allows you to create a copy of the TCP/IP network stack -all the way from the Ethernet interfaces (L2), routing tables etc.
This is a guest post by Suryanarayana M N V. Having led teams working on Networking protocols, Surya has in-depth knowledge of networking. He has keen interest in the areas of Network Virtualization and NFV.
The most common NFV product that I had come across is in security domain viz., firewalls. To get an idea on how good they are, I checked the Juniper, PaloAlto & Fortinet Virtual Firewall products.
If you were to ask someone “what is the most popular open source hypervisor” chances are that the answer will be KVM. Indeed KVM (or Kernel-based Virtual Machine) has played a key role in the open source Linux based virtualization environment. However is it really a hypervisor? Moreover, can KVM by itself run virtual machines? We will delve more into such questions in this blog. We will also understand the relationship between KVM and QEMU (Quick EMUlator).
In the previous blog of this series we saw that using Linux bridge we can connect a virtual Ethernet port of a VM to the physical Ethernet port of the hypervisor server. Let us now focus a bit more on these virtual ports to see what happens behind the scenes to make virtual networking actually work.
Software defined networking (SDN) is the current wave sweeping the networking industry. And one of the key enablers of SDN is virtual networking. While SDN and virtual networking are in vogue these days, the support for virtual networking is not a recent development. And Linux bridge has been the pioneer in this regard.
Log statements help record the flow of an application’s execution. Hence they are an important part of software coding process. For the Java language the common Log API libraries are Java Util Logger (commonly known as JUL), Apache Log4J, SLF4J etc. While these libraries support many advanced capabilities, most developers only use a handful of features. For example, ability to send log messages to files and the ability change log levels dynamically etc.
In this blog I will compare JUL against SLF4J and focus on these above mentioned features. Many will argue that this is not a fair comparison since SFL4J is really a facade and supports JUL as well. To clarify, I will compare the SimpleLogger that is bundled with SLF4J against direct JUL usage.