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Thursday, May 18, 2017

Starting IS-IS routing protocol without CCNP training

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, this note might save you some time.

Wednesday, April 26, 2017

How do we repair a broken submarine fiber cable?

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 was created and published by TE SubCom. I summarize the key steps mentioned in this video, and I also added some of my own notes all in this post. I hope this post together with the original video would help you to understand the repairing operation as well.

Wednesday, March 29, 2017

Clear configured allowed VSAN list on trunk ports of Cisco MDS

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.

Thursday, March 23, 2017

Cisco IOS/IOS XE Vulnerabiliy announced. Disable TELNET fast

This is just a short notice for you in case you are not aware of it. Cisco announced a vulnerability on Cisco IOS and IOS XE operating system. For short, you only have to disable incoming TELNET service onto the router itself to avoid this vulnerability. You can use Secure Shell (SSH) instead for remote management. SSH is not vulnerable in this problem.

The Jin-Dai Bridge (錦帶橋) in Dahu Park (大湖公園).
Taipei City, Taiwan.

Wednesday, August 24, 2016

Do more with “the same”

To emphasis the effectiveness of a new tool, we always hear some people say it would make you “do more with less”. This is so attractive to Chief Officers. How would the other staffs think about this?

Dongshan River Water Park (冬山河親水公園).
The venue of  Yilan International Children's Folklore and Folkgame Festival (YICFFF, 宜蘭國際童玩藝術節). Yilan County, Taiwan. 

The problem of “do more with less”

With the word “less”, what does that mean? Does that imply we don’t need that much budgets anymore? Does that imply we don’t need more hardware? Does that imply the workforce would be cut down?

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