Worth Reading: Legacy software and Evolution
In case you’re wondering why we’re stuck with old stuff like TCP, IPv4, OSPF, and a few other bits and pieces that were invented decades ago when we could be using the glitzy controller-based software-defined whatever, read the blog post by Martin Sustrik. He talks about software, but we’re facing the same challenges in networking.
IETF 98 Report
The IETF meetings are relatively packed events lasting over a week, and it’s just not possible to attend every session. Inevitably each attendee follows their own interests and participates in Working Group sessions that are relevant and interesting to them. I do much the same when I attend IETF meetings. The IETF met for IETF 98 in Chicago at the end of March, and from the various sessions I attended here are a few personal impressions that I would like to share.OpenVPN – TCP or UDP tunneling?
Spoiler alert: You most likely would want to use UDP tunneling!
An OpenVPN tunnel runs over IP and can encapsulates VPN traffic into either a UDP or a TCP connection. To understand the pros and cons of each, we first need to have an understanding of them both.
TCP
Transmission Control Protocol is the dominant protocol there is for most daily stuff happening on a network. It has some very interesting features built-in which makes it very resistant to network packet loss, packet reordering, packet duplication, unintentional packet corruption and even link congestion. Despite it being not perfect1, it’s survived the test of time and it’s not going anywhere in near future.
All those features however come at a price. A typical TCP packet has a header size of 20 bytes. Assuming you’re using IPv4, You also get a 20 bytes IP header added on top of it. So at least 40 bytes in each TCP packet is the header data that comes before the actual payload.
UDP
Unlike TCP, User Datagram Protocol does not come with much features. It comes with a checksum header for packet integrity but connection reliably as a whole is not guaranteed. In Continue reading
Site News: RSS Feed Update
Do to ongoing problems with RSS feed hosting from Feedblitz, I am migrating the RSS feed to a new provider on Wednesday, 12 Apr 2017.
This may cause previously ‘read’ articles in your RSS feed to show as new. Its depends on how your RSS Reader the articles as “new” and what criteria they use to detect new/read.
Apologies in advance for the inconvenience but cannot continue with the unpredictable service, poor support and low quality website that Feedblitz has delivered over the last six months.
The RSS subscription is URL is unchanged http://feeds.etherealmind.com/etherealmind which should require no changes on your part.
The post Site News: RSS Feed Update appeared first on EtherealMind.
Converge your network with explicit congestion notification
Every now and again, we like to highlight a piece of technology or solution featured in Cumulus Linux that we find especially useful. Priority Flow Control (PFC) and Explicit Congestion Notification (ECN) are exactly such things. In short, these technologies allow you to converge networks and save money. By supporting lossless or near lossless Ethernet, you can now run applications such as RDMA over Converged Ethernet (RoCE) or RoCEv2 over your current data center infrastructure. In this post, we’ll concentrate on the end-to-end solution for RoCEv2 – ECN and how it can help you optimize your network. We will cover PFC in a future post.
What is explicit congestion notification?
ECN is a mechanism supported by Cumulus Linux that helps provide end-to-end lossless communication between two endpoints over an IP routed network. Normally, protocols like TCP use dropped packets to indicate congestion, which then tells the sender to “slow down’. Explicit congestion notification uses this same concept, but instead of dropping packets after the queues are completely full, it notifies the receiving host that there was some congestion before the queues are completely full, thereby avoiding dropping traffic. It uses the IP layer (ECN bits in the IP TOS header) Continue reading
EP13: Colin McNamara DevOps expert and cloud architect shares with us on how to secure your future in IT!
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