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Show IP Protocols

Li-Ji Hong (洪李吉)

Build Your Dream Internet with Li-Ji Hong (洪李吉)

education training

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BGP Millionaire

Show IP Protocols ·

2025/05/04

【 BGP Millionaire】I used this tool to generate this plot.Plot Range: 01-Feb-2025 0001 to 30-Apr-2025 0030.Recently I observed and noticed that, global IPv4 BGP table size has already grown over 1 million entries, around February to April time in this year, 2025.I want to clarify this first. By the number “one million” I mean exactly the number “1,000,000”. I understand most people are more familiar with another number “1,024*1,024=1,048,576” as “1 Mega” something. We do not have that many BGP

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How do we fix a broken submarine fiber cable?

Show IP Protocols ·

2025/01/11

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

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BGP AS-Path Filtering, Demonstration

Show IP Protocols ·

2025/01/05

【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.

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Cisco IOS Live demo: Filtering with Regex

Show IP Protocols ·

2024/12/31

【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.

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Cool Immersive Cooling

Show IP Protocols ·

2024/06/05

【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 TweetThe cooling liquid looks like water to me. However, I know this simple physics that water is electrically conductive. Even a drop of water on a running circuit will

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Breaking 100K Entries is the Global IPv6 BGP Table

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2020/12/06

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

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Three possible scenarios of Software Defined...

Show IP Protocols ·

2019/12/07

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

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Where do we use Cisco Wildcard Masks?

Show IP Protocols ·

2019/11/18

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. When we define selected source or destination IPv4 addresses for an Access Control List (ACL), we use Wildcard Mask. Here is an example for Cisco IOS and IOS XE. ip access-list extended ACL-NAME deny tcp 172.16.9.0

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Revised post: Covering Subnet Calculator to...

Show IP Protocols ·

2019/11/05

This tool is an update to my previous post: Simple visual tool to calculate Cisco IOS Wildcard Mask Notes for Cisco IOS Wildcard Mask You can simply assume Cisco IOS Wildcard Mask are derived by mapping 1s to 0s and 0s to 1s of equivalent subnet mask in binary notation. By definition, “0” bits in a wildcard mask denote the bits you must match the base prefix, and “1” bits denote the bits you simply don’t care. All subnet masks must begin with contiguous “1”s, and rest of the digits must be

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Global BGP IPv4 table is around 800K in size

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2019/11/03

This week the global BGP IPv4 table is around 800,000 entries in size. I bring this up just to give you a head-up and say a “Wow”. I don’t want to make you worry about the number. This is not my intention. I still remember the “old good time” when I had installed a BGP router (Cisco 3660) with 256 Megabytes of DRAM memory in year 2001. At that time, the BGP table is below 150,000 entries so that router worked well. Screen capture of CIDR REPORT website on November 3, 2019 The size of router

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Scanning active IPv4 addresses is difficult? Simpler...

Show IP Protocols ·

2019/10/20

It is always a best practice to keep full track of all IP address assignments inside our local area network. From time to time, it might also be a good idea for security purposes to check whether we have any hidden nodes inside our network. To discover any node with active IP addresses inside our network, we might imagine that we must acquire powerful tools such as Cisco Prime Infrastructure before we can achieve anything. In fact, it might be much easier than you have expected. Let me show you

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CCNA 2020, My summary of changes

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2019/06/27

Cisco recently announced major changes of certification programs and they all will take place on February 24, 2020. In this post, I am giving you my quick summary on CCNA alone. CCNA Exam Changes (200-301) The official new exam name for CCNA 2020 is “Cisco Certified Network Associate v2.0 (CCNA 200-301)”. I know it is quite confusing since CCNA exams has already been changed for a couple of times in recent years. I will call this 2020 CCNA by its exam code “200-301” instead. Compared to

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Google is terminating Google+ service

Show IP Protocols ·

2019/02/14

Hi, this is Li-Ji Hong speaking. We now know Google is terminating Google+ service. I understand that many of you came from Google+ to find and visit my web site “Show IP Protocols”. To keep updated and connected to my web site “Show IP Protocols”, I recommend you adding at least one of these three services: Twitter, Facebook, and Email subscription. Twitter Number 1 is Twitter. In my opinion, Twitter is so much like Google+. I will keep posting new contents on Twitter even after Google+

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400G Ethernet, My Observation Notes

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2018/11/04

I saw a post about Cisco has announced 400G Ethernet switch products. 400G Ethernet means the bit rate can be up to 400 Gbps. Here are some of my observation notes on 400G Ethernet products. Cisco announced four models of Nexus 400G switches Screen capture onCisco.com In the product page, Cisco announced 4 new models of Nexus switches with 400G Ethernet capability. Nexus 9316D-GX is for Cisco ACI Spine. Nexus 93600CD-GX is for Cisco ACI Leaf. Nexus 3408-S and Nexus 3432D-S are non-ACI

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Bank lost 1 million US Dollars because of outdated...

Show IP Protocols ·

2018/07/25

A recent news was about hackers hacked into a Russian bank because of outdated routers. When I saw the keyword “router”, I felt that I must dig further about what really happened. What I have understood now The victim is PIR Bank. One of the suspects is MoneyTaker. After the breach, PIR Bank hired company Group-IB to do the clean-ups, recovery, and investigating how the hackers got into their internal network. Up to this moment, Group-IB disclosed hackers exploited the outdated routers of PIR

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BGP Injection instead of Leak, my observation notes...

Show IP Protocols ·

2018/04/26

After reading articles by Doug Madory, and by Louis Poinsignon, here are some notes I observed and learned. [What happened in this incident?] Hackers somehow made some BGP routers of “eNet” to falsely announce that they own the following 5 IP subnets, which are indeed NOT belonging to “eNet”. The true owner is Amazon. To be more specific, they are for Amazon’s Route 53 DNS name resolution services. 205.251.192.0/24 205.251.193.0/24 205.251.195.0/24 205.251.197.0/24 205.251.199.0/24 The

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Prepare Python 2.7 on Microsoft Windows using PowerShell

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2017/09/10

Everyone today talks about the programming language Python while discussing Software-defined Networking (SDN). Since Python is so popular, it would be a good idea for network administrators to know more about Python. First thing first. I talk about how I prepare Python running environment on Microsoft Windows. It would be nothing special if I only download the installation software from Python official web site by mouse clicking. Instead, I use PowerShell to download and install for me. That is,

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Starting IS-IS routing protocol without CCNP training

Show IP Protocols ·

2017/05/18

The routing protocol Intermediate System to Intermediate System (IS-IS) is an advanced and robust link-state protocol used in many service provider networks. Most of the other enterprises I know of prefer to use protocols like OSPF or EIGRP instead of IS-IS. Therefore, enterprise administrators might not be familiar to this protocol at all. Here I want to share my short note to start IS-IS quickly without digging into protocol details. In case you must configure and maintain an IS-IS network,

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How do we repair a broken submarine fiber cable?

Show IP Protocols ·

2017/04/26

On April 22, 2017, one segment of Asia-Pacific Cable Network 2 (APCN2) that serves Taiwan’s major Internet connectivity with Japan, Europe, and America, was broken. According to some news sources, it might take one month just to fix this outage. I live in Taiwan, and I do feel the Internet speed became slow after this outage. I was wondering how could the repairing take one month. I want to know how to repair a broken submarine fiber cable. I searched on Google and I found this video. This video

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Clear configured allowed VSAN list on trunk ports of...

Show IP Protocols ·

2017/03/29

A friend asked a good question about how this command works on Cisco MDS FibreChannel switch: “switchport trunk allowed vsan all”. To my surprise, I cannot find any specific official documents to explain it clearly. I did some experiment on one Cisco MDS 9148. And here is my conclusion. Bay, beach, and cliff near Chung-De Station. (崇德海灣). Hualian County, Taiwan. To clear whole allowed VSAN list and make every VSAN allowed at the same time, use “switchport trunk allowed vsan all” in the

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