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How to enable IPv6 support on a Cisco 3560 switch

If you have tried configuring IPv6 on a Cisco 3560 switch, you may have noticed the ipv6 commands aren't available by default. This often catches me when I am working on a new switch that has never had IPv6 enabled. I just had this happen tonight, so I figured I'd write a brief how-to with some background info thrown in.

Where are the IPv6 commands hiding?

Cisco 3560 switches have a feature called Switch Database Management (SDM) templates. There are various templates that can modify the allocation of system resources to better support different features. What does this mean? By default, a small catalyst switch is built to support 8 routed interfaces and 1024 VLANs. It's not generally used to route OSPFv3 and BGP (though, it can do that). So as a result, the system resources are evenly distributed among the various functions to accommodate a common set of tasks.

Service Config - Error opening tftp://

Command Line

If you have worked on a newer Cisco IOS device, you may have seen the following error messages:

%Error opening tftp:// (Socket error)
%Error opening tftp:// (Socket error)
%Error opening tftp:// (Socket error)
%Error opening tftp:// (Socket error)

If you are wondering what these messages mean, it is the result of the config service being enabled by default in some IOS versions. Read on to learn about how it works and how to disable it.

Cisco 4500 Series Sup7e Install Notes

One of my projects at work is to replace a couple switches with newer (and larger) 4507R+E with Sup7e. I love projects like this because they're relatively straight forward, but mainly because they are fun! Who doesn't like unboxing a $60,000USD switch and firing it up? It's like a Cisco birthday or something.

Anyway, while configuring this thing, I've noticed a few quirks... idiosyncrasies? "Features"? Whatever you call them, they're new to me and I felt like blogging about it.

SD Memory in a Supervisor

First, just an observation: Cisco now has Secure Digital (SD) memory in a Supervisor. You might be thinking "yeah, I read about that when the Sup7e came out..." However for those who were in the dark, now you know. Here's a picture to share: 

Use the Configure Replace command to speed up your labbing

I've been labbing quite a bit lately, working on Narbik's R&S workbooks, and I've been rebooting my rack after nearly every lab to clear things out. Well, I was perusing the Interwebs and a forum post reminded me of the config replace command. Sheesh! I wish I would have remembered that a few hundred reboots ago...

Even though I knew about this command, and have even included it in a blog post or two in the past, I had forgotten about it since I wasn't using it all that often. So, just in case someone else out there has forgotten about it, I figured I'd do a quick write up demonstrating the command in action and hopefully jostle some memories (or just help me remember if I forget it again).

Here is a 1841 router that used to be R5, but I changed it's hostname to Testing and did a no shutdown on all it's interfaces. Follow the config below for the usage:

Tekcert's 3rd Birthday

Three years ago today, was launched! 2012 was a busy year, both online and offline. I just wanted to write a quick blog post to recognize some milestone and throw a few statistics out there.

I'd like to begin by saying Thank you to all the readers for the support and participation with the forums and comments. It is a pleasure creating a place online that intelligent people can share knowledge and help each other out.

I have received a lot of encouraging messages that have been thankful and kindhearted to keep up with the posting. Many people have shared that they love the blog. I appreciate the kind words and encouragement and will do my best to keep up with the blog posts in between studying for the CCIE Lab exam.

So, that brings us to the stats! Here are some notable numbers for the past year:

Cisco IP Phone Vulnerability Enables Remote Eavesdropping

A recent Cisco Security Advisory details a vulnerability that allows "an arbitrary code execution...that could allow a local attacker to execute code or modify arbitrary memory with elevated privileges." In other words, if you have a Cisco 7900 series IP Phone on your desk, it can be totally pwnd.

This might not come as a surprise to those who have worked with these devices or other IP phones with programmable features. It's basically a little computer with a plastic phone shaped box wrapped around it. If this is a surprise to you or if you don't believe it, check out the video demonstration below.

Unlock your old iPhone


If you happen to have an old iPhone laying around that you no longer use and want to sell or repurpose it, then this bit of information might help you out. You might be asking "what does unlocking an iPhone do?" Good question, unlocking an iPhone (not to be confused with Jailbreaking) lets you use it on other cellular provider networks. For example, if you purchased an iPhone 4 a couple years ago for use with AT&T's network, you would only be able to use it on AT&T's network unless you unlocked it. After unlocking it, you can use that phone on other cellular provider networks that use similar technology as AT&T (GSM), such as T-Mobile.  If you want to use it on a CDMA network, such as Verizon, then you are out of luck as the technologies are different. So, that leaves us with the point of this post: How do you unlock your iPhone?

CCIE Boot Camp Review - Micronics (Narbik's) 12-Day

Studying for your CCIE? If you are, then you might be planning to take a boot camp to help you prepare. A lot of candidates use boot camps to help them prepare and there are many choices available to routing and switching candidates in particular. If you haven’t taken a boot camp yet and are still considering which one to attend or whether or not to attend one at all, then this blog post is written for you.

Save yourself some time with the default interface command

Command Line

If you configure Cisco equipment on a regular basis, you might find yourself in a situation with a large number of router or switch ports that need to be reconfigured. There are several ways you can prep your switch ports to complete your task:

  • You could do a "show run" and then build a script that includes the "no" form in front of each of the old commands, then apply your new script.
  • You could simply overwrite the old config with the new and then go do the no form of the stuff you don't want after the fact.
  • You could erase the startup-config then reload the switch and start from scratch (assuming the device isn't in production anymore).

There are probably another half dozen different ways of simply erasing the config and starting over, but there's one more option that this post is focused on today: the default interface command.

OCZ Technology 128GB Vertex 4 Series SATA 6.0 GB/s 2.5-Inch Solid State Drive (SSD)

I just picked up an OCZ Technology 128GB Vertex 4 Solid State Drive (SSD) to drop in one of my machines at home. It doesn't need much space, so 128Gb size should be more than enough.

The main reason for picking this up is the speed. The box that this is going in currently hosts several VMs and the storage is on a NAS. After installing this, some of that storage will be offloaded onto the SSD, which should make for some speedier response times than a 1Gb Ethernet connection to some spinning disks.

SecureCRT Feature - Alt Select

If you are a SecureCRT user, here's a feature that might save you some time. Let's say you have a list of information in your terminal window that you'd like to copy - perhaps the output of "show ip interface brief." However, instead of the whole output, you only want the list of interfaces, not the rest of it. Normally, you would just highly the whole output of information and then either paste it as is or paste it in a notepad window and delete all the stuff you don't want. 

This gives you the following output:

R2#show ip int bri
Interface                  IP-Address      OK? Method Status                Protocol
Serial0/0                  unassigned      YES unset  up                    up      
Serial0/1                  unassigned      YES manual up                    down    
Serial0/2                  unassigned      YES unset  up                    down    
Serial0/3                  unassigned      YES unset  administratively down down    
FastEthernet1/0          YES manual up                    up      
FastEthernet2/0     YES manual up                    up      
Multilink1        YES manual up                    up     

Well, there is another way. A much cleaner way...

SecureCRT Feature - Chat Window

SecureCRT Icon

If you are a SecureCRT user, you might find a certain feature useful when configuring multiple devices via CLI. The feature is called Chat Window and it's not what it appears at first glance.

When I first saw the Chat Window feature listed in the View menu, I assumed it was some sort of remote tech support option or a way to collaborate with multiple users. Although it is certainly possible to use it to "chat" using the IOS Send command, it is far more powerful as a quick way to configure several routers or switches at the same time. 

Here's how it works...

My journey to become a CCIE

I've been interested in technology for as long as I can remember. From my early beginnings of learning how to navigate the DOS command line interface on my dad's computer while he was off at work, to building my first PC (with 8Mb of RAM!). I've always had an interest and a knack for this stuff.

Over the past decade, my interest in networking technology has grown significantly. In 2001, I earned my CCNA while working at Cisco (on contract) and a few years later installed my first 6509 in a global financial company. Several certifications followed down the road including the CCNP and CCAI. I now teach Cisco curriculum part time while working as a Senior Network Engineer for a mid-size enterprise. My drive to learn has never stopped, in fact it just keeps growing the more I am exposed to this stuff.

The time has come to take it to the next level.

Several months ago I made the decision, after some serious research and discussions with my wife, to begin studying for the CCIE Routing & Switching Exam. I started by researching and reading everything I could find regarding the exam - Cisco's official exam page, other blogs that detail how they approached the exam, podcasts talking about the exam, etc. I spent a good month reviewing my options before I finally made the decision that absolutely, without a doubt I am going to go for it - no matter what it takes.

I've written this blog post to share my experience so far and hopefully help others in a similar situation to make the go-no-go decision.

Packet Pushers Show 114 – Real-Life CCNP With Jeremy Cioara

Studying for your CCNP? Like podcasts about networking stuff? Like to listen to Jeremy talk about certifications? Then you have to check out this podcast where Jeremy discusses the CCNP and other certification stuff with Packet Pushers hosts Ethan Banks and Greg Ferro.

Upgrade your Macbook Pro to a 1 TB hard drive

If you bought a Macbook Pro in the last couple years, like me, you may be pushing the limits of the factory installed 250Gb hard drive. So far, the factory installed Toshiba hard drive has been rock solid, no complaints. I just need more space than 250Gb.

As of right now, the current Macbook Pros come with 500Gb or 750Gb hard drives (with an option to upgrade to 1Tb).  Back when I bought, they had 250Gb and 500Gb options. If you want more storage in your Macbook Pro, read on!

Select a Hard Drive

The first decision you have to make when buying a hard drive is how much space do you want?

I figure storage is relatively cheap, so why not go as big as possible? After a bit of research, the disk I chose to go with is the Western Digital Scorpio Blue 1 TB Hard Drive. The decision was mainly based on the size of the disk, but several reviews I read all stated the disk is quiet and reasonably fast for it's size. The price is right as well (right around $100US).

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