How do we fix a broken submarine fiber cable?

A submarine cable cutting incident happened recently at the Baltic Sea. Another similar incident also happened north of Taiwan. 

I wanted to know more about how to repair a broken submarine fiber cable. I did my research on the Internet. I summarize my findings and list the key fixing steps below.

1. The submarine cable was working.

Initially, the working submarine cable was below the sea water and above the seabed. The submarine cable follows and fits the terrain of seabed.

2. A fault happens.

Examples of faults are punctured insulation, fiber core breaks, and cable cut.

Faults could be natural factors, such as the aging of cable itself, earthquakes, falling rocks, and shark bites. Faults could also be human factors, such as fishing nets dragging, anchoring hits, and malicious sabotage.

BGP AS-Path Filtering, Demonstration

How many of you are working with BGP in your daily job? Let me know in the comments below this post.

I also created a live demonstration about filtering based on BGP AS-Path with Regular Expressions. I hope it is helpful to you.

Cisco IOS Live demo: Filtering with Regex

I share my technique about how I use Regular Expression (regex) to filter out show commands' output.

How do you like this video? Let me know at the comments area of this post, or on YouTube.

Cool Immersive Cooling

I was so amazed about this cooling technology. It is new to me.

Thinking about liquid cooling for servers and networking devices, coming into my mind are tightly sealed water pipes around the circuit boards. This is different. The circuit board and everything simply immerse in liquid.

Cisco Service Provider Tweet

Breaking 100K Entries is the Global IPv6 BGP Table

This year, 2020, around November I started to see the global IPv6 BGP Table is getting more than 100K entries. Although the number is going above and under 100K from time to time, starting from the end of November I can safely say it is breaking 100K entries right now.

This is an interesting milestone for IPv6. That means a massive majority of people are using IPv6 today. I want to note down this moment. And I want to share 3 of my own observations about the IPv6 BGP table.

Three possible scenarios of Software Defined Networking (SDN)

Software-defined networking (SDN) is an approach to create a centrally controlled programmable packet network. Any protocols with the same approach could be considered as SDN as well.

For open protocols, we have one popular standard protocol “OpenFlow” talking among the central controllers to all managed networking devices. Open Network Foundation (ONF) defines OpenFlow protocol.

In fact, vendors also have developed proprietary protocols to implement this same approach. For example, Cisco’s ACI is a proprietary SDN solution.

Here I summarize 3 most probable scenarios when we deploy SDN.

Where do we use Cisco Wildcard Masks?

People might still be interested in about Cisco Wildcard Masks. I try to summarize interesting information about Wildcard Masks in this post.

Use Case 1: IPv4 Access Control Lists on Cisco IOS, IOS XE, and IOS XR

Wildcard masks are for us to select only subsets of IPv4 addresses.