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Friday, November 29, 2013

Visualizing Wildcard Mask: Simple Calculation Tool in Excel

(Original subject: "Simple visual tool to calculate Cisco IOS Wildcard Mask")

I create this tool for you to easily calculate equivalent Wildcard Mask for any given IPv4 address and subnet mask.

You can make use of this tool when you have to configure Cisco IOS Access Control List, "network" command in routing protocols, and you can also do a quick double-check about whether the wildcard mask is matching the designated subnets or not.

In fact, this tool is revised from another tool I have posted before.

Tuesday, October 29, 2013

Cisco NX-OS vPC (Virtual PortChannel) Configuration Notes

Water spring reflecting a rainbow.
Youth Park (青年公園) (Google+). Taipei City, Taiwan
To enable Multi-chassis EtherChannel (MEC) on Cisco Nexus data center switches, the only option left for you is to enable Virtual PortChannel (vPC).

Virtual PortChannel is not that easy for people to configure correctly by hand. Even In this “Quick” vPC Configuration Guide, we still have to do 8 long steps before we have some working vPCs. A little bit frustrating when we look at it for the first time.

Here I just want to point out one aspect to make you feel better about vPC.

Friday, October 4, 2013

Cisco NX-OS MOTD configuration and verification

Tropical feel in Taipei Botanical Garden (台北植物園) (Wiki).

In NX-OS, the command to configure MOTD (Message of the Day, Wiki) banner is exactly the same as IOS.

Thursday, October 3, 2013

Displaying text file contents on Cisco IOS and NX-OS

Looking over Taipei Railway Station (台北車站) (Wiki), to northern part of Taipei City.
[Cisco IOS]

For Cisco IOS platforms, we use the command more.

Tuesday, September 24, 2013

Enable Jumbo Frame function of Cisco Nexus 5000 and 7000

An autumn view of Taipei Campus of National Taipei University (NTPU).

For Data Center networking, and in most of the cases, jumbo frames should be enabled. However, Jumbo frame feature is not enabled by default. So the next question would be "How to enable them in Cisco's Data Center switches such as Nexus 5000 and Nexus 7000 families"?

Saturday, September 21, 2013

No more CMP on Nexus 7000 next-generation supervisor modules Sup2 and Sup2E

Connectivity Management Processor (CMP) is like an embedded terminal server dedicated for a single Nexus 7000 data center switch. I personally like this feature because we do not have to prepare another set of terminal server just to monitor the console output while we reboot the switch.

However, starting from Supervisor 2 (Sup2) and Supervisor 2 Enhanced Module (Sup2E), CMP hardware is removed from supervisor module itself.

I am not sure whether this feature will come back in the future or not. For the time being, we will have to prepare terminal servers or reserve asynchronous serial ports for Nexus 7000 switches administration.

[Supervisor 1]

Captured on


CMP Status LED




Link LED




CMP MGMT Ethernet port

Monday, September 2, 2013

Strange "rollback" failure of Cisco Nexus 5500

Left to right: "Taipei 101" and "International Trade Building (ITB)"
Taipei City, Taiwan.

After doing "write erase" and reboot, Cisco Nexus 5500 will fail to rollback even to its previously saved configuration files of checkpoints!

Thursday, June 13, 2013

Propagation of BGP Routing Information among Routers belonging to Different Companies

Another photo of Jih Yueh Shan Jing Leisure Farm (日月山景休閒農場).
Changhua County, Taiwan (Google Plus)

Yes! Most of the books mentioned this scenario as External BGP (sessions).

Friday, June 7, 2013

Cisco UCS C210 in Greenplum MR Hadoop Reference Configuration

Major hardware components and interconnection of Greenplum MR Hadoop Reference Configuration. This diagram is a screen capture of Figure 5 of  this White Paper on
In fact, I shared the following content in this Google Plus Community: Using Cisco UCS. If you like to explore more about Cisco UCS, welcome to join us anytime!


I used to say UCS C Series are designed for "smaller deployment". However, recently I found an interesting application in DCUCD v5.0 training materials,  which contradicts to what I said before. Greenplum MR Hadoop Reference Configuration is a quite-large deployment with UCS C Series only. I really should correct my saying from now on!

Thursday, June 6, 2013

New updates to be in Cisco ISE 1.2

Jih Yueh Shan Jing Leisure Farm (日月山景休閒農場).
Changhua County, Taiwan (Google Plus)

I summarize the key points I learned from this Q&A on Cisco web site.

[New Features]
  • MDM Integration
  • Device Feed Service
  • Doubling of Scale and Performance
  • Bootstrap Wizards

Wednesday, June 5, 2013

Changing to Google+ Comments on July 1, 2013

White Rock Lake Bridge (白石湖吊橋), Taipei City, Taiwan. (Google Plus)
Sooner or later, I believe Google would convert everything into Google+. I plan to convert the commenting system of this blog to Google+ Comments on July 1, 2013. I believe it will make this blog more interesting this way.

The biggest impact to readers is no more "Anonymous" comments. However, you can create almost "anonymous" Google+ profile to comment in this blog. Here I share some good posts about how to limit the information exposed on Google+ profile, so you can keep your anonymousness.
Before I do this change, you can still post Anonymous comments below this post. I am still open to all feedbacks about this change. Any comments are welcome!

Tuesday, June 4, 2013

Cisco ISE Licensing in plain words

Feng-Le Sculpture Park (豐樂雕塑公園). Taichung City, Taiwan. (Google Plus)
Maybe I can summarize the description in this post as below.

No worry at all when exceeding device license count.

You can continue to manage and use ISE to authenticate and authorize network uses even when you run out of licenses count. The only inconveniences are the annoying warnings.
If you've reached limits of your current license, you also need to obtain new license. It could be completely new license, or an upgrade. ISE implements the concept of soft limits. So the system will throw "license enforcement" alarms (see

Important note: ISE is not locked when license is overhelmed.

Wednesday, March 27, 2013

Making your Cisco Instructor Kit work

Divine Tree of Mingchih Forest Recreation Area.
Yilan County, Taiwan
Many new Cisco instructors I know of have some problems about downloading and opening DRM-protected training materials. Maybe all you need is this hint: an official guide and recorded video on

Recorded Tutorial: Want to review the important activities under the program?  This step-by-step tutorial will take you through the following key tasks:
  • Updating your ID on the certification tracking tool
  • Downloading your LockLizard viewer and LockLizard license
  • Downloading and viewing your instructor kits

Monday, February 18, 2013

Video: Hacking Cisco Phones

Hackers demonstrated how to transform a Cisco phone (with vulnerabilities firmwares) into a audio recording station for spying without loosing phone's original capabilities.


Wednesday, January 30, 2013

Avoiding human errors with Cisco NX-OS "Grace Periods"

Looking out to Guishan Island (the left top far)
Taken around Northeast Coast National Scenic Area (東北角海岸國家風景區), Yilan County, Taiwan.
Cisco offers “Evaluation” time intervals (Grace Periods) for some features of Cisco NX-OS on Data Center switches such as Nexus 7000 or Nexus 5000. It is a nice design because customer can evaluate whether those specific features are suitable for their needs or not, before they really buy that license. This is also very useful for PoC (Proof of Concept) installation.

It is really simple to start evaluation. First we enable evaluation grace periods by “license grace-period” command. Then we only have to type “feature X” commands at the CLI as if we have bought the license.

Sunday, January 20, 2013

Configuring Cisco UCS Native Zoning (Video)

A plane was taking off Green Island Airport, Taiwan.
Starting from UCS Manager 2.1, you can configure FC Zoning to protect FC network. This video demonstrate how to configure FC Zoning at UCS Manager side.

Sunday, January 13, 2013

New Google Plus Community: "Using Cisco UCS". Welcome!

A rock near Green Island, Taiwan
Are you deploying Cisco UCS as your Data Center Server solutions? Are you administering Cisco UCS pods? Are you designing solutions based on Cisco UCS? Or, are you just interested in what Cisco UCS is? Here I have a good news for you.

+Michael Gaskin and I created a new Google Plus Community named "Using Cisco UCS". You can share your experiences, ask a question, or answer other people's question, anything about Cisco UCS in one place.

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