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So You Wanna Be A Network Engineer?

This is how I spent early Monday morning after I got paged.  Only the names and addresses have been changed:

Site Support [12:18 AM]:
U there?

Me [12:18 AM]:
Yes.  You paged?

Site Support [12:18 AM]:
Entire network is down at site x.

Me [12:18 AM]:
You’re physically at site x right now?  Not VPN?

Site Support [12:18 AM]:

Me [12:18 AM]:
Then entire network is not down. Otherwise we would not be having this IM chat.

Me [12:20 AM]:
What leads you to believe that the network is down?

Me [12:23 AM]:

Site Support [12:23 AM]:
No one can get to internet.

Me [12:23 AM]:
Intranet is working?

Site Support [12:24 AM]:
yes. Intranet sites up. Internet DOWN.

Me [12:24 AM]:
Give me a URL for an Inet site you can’t reach.

Site Support [12:25 AM]:

Me [12:25 AM]: ? Is that the full URL?

Me [12:27 AM]:
Dude. It’s 12:30 am on a Sunday here. Can you verify the URL for me?

Site Support [12:28 AM]:

Me [12:28 AM]:
I’m going to assume that this is http.

Me [12:28 AM]:
I can open port 80 on from your user switch.

Site Support [12:29 AM]:

Me [12:29 AM]:
That means that the network is not blocking/dropping traffic to

Site Support [12:29 AM]:
but internet is still DOWN!!!

Me [12:30 AM]:
I need your IP address.  Please cut and paste into IE and tell me what IP address shows at top of the page.

Site Support [12:31 AM]:
Your IP Address:

Me [12:32 AM]:
Okay.  That website that’s showing you your IP address…

Me [12:32 AM]:
…it’s on the Internet.  Network is NOT down for your site.  Internet is NOT down for your site.

Site Support [12:34 AM]: is DOWN!!!

Me [12:35 AM]:
Not from a network standpoint it is not. You might have a proxy issue, but I don’t mangage those boxes so I can’t help with that.

Site Support [12:35 AM]:
Who do I page for that?

Me [12:36 AM]:
No idea.  NOC can help with that.  Is this the only site that is unreachable?

Me [12:38 AM]:

Me [12:38 AM]:
I just browsed to the site from my desktop.  What do you see when you go to that site?

Site Support [12:38 AM]:
nothing its down

Me [12:38 AM]:
So you don’t see “website offline for maintenance”?

Site Support [12:40 AM]:

Me [12:40 AM]:
Yes you see “website offline for maintenance”?

Site Support [12:40 AM]:

Me [12:40 AM]:
This is a third-party website that is down for maintenance.  This has nothing to do with us.

Me [12:41 AM]:
I assume that it will restore once they are done with their maintenance.

Me [12:41 AM]:
Please have NOC close ticket.  I am going back to sleep.

Site Support [12:41 AM]:
Who do I page for this?

Me [12:42 AM]:
Huh?  For what?

Site Support [12:42 AM]: down

Me [12:42 AM]:
No one.  Not unless you want to call and ask them when their maintenance will be done.

Site Support [12:43 AM]:
How long is mantenance? Site cannot work.

Me [12:44 AM]:
I do not work for so I cannot answer that.

Site Support [12:44 AM]:
Who can?

Me [12:44 AM]:

Me [12:45 AM]:
Good night.  Please have NOC close ticket.

Packet Pushers Podcast

I listen to quite a few podcasts.  Podcasts like TWIT, Buzz Out Loud, Uhh Yeah Dude, The Skeptic’s Guide to the Universe, You Look Nice Today, and many others fill my ears during my commute, while I do yard/house work, and often when I’m designing my latest Visio opus.  The vast majority of the podcasts that I listen to are either news or entertainment shows (or some mixture of both).  For a long time now, I’ve often yearned for a podcast that covered networking topics.  But everytime I thought about what that show would be like, I decided that it would probably be nearly impossible for anyone to create a compelling networking/Cisco podcast.  It would be pretty hard,  let alone boring,  to discuss configuration without video.  There exists some great video shows out there like TechWise TV, but I’ve never stumbled across a networking-centric audio podcast.  Until now.

Packet Pushers Podcast (someone loves alliteration) is an audio podcast covering all things networking.  The show is hosted by Greg Ferro, an Australian born, UK based, CCIE who runs the EtherealMind website. Joining him on a regular basis are Dan Hughes, an Irish blogger (The Roving Network Engineer’s blog) and CCIE, as well as Ethan Banks (Packet Attack blog), a CCIE from this side of the pond.  Those three engineers form the nucleus of the podcast.  They bring in interesting voices from the networking world each week to join them in discussing networking topics.

The podcast is currently on episode 16 and even has some shorter segments (“Runts”) as well as a newly formed spin-off (“Packet Pushers Unplugged”) podcast which covers wireless networking.  In the span of just a few months, they have created quite a bit of content.  I recently saw a tweet stating that the show has about 1500 weekly followers.  Not bad for a new, niche podcast.

I had actually heard about PPP about the time that it launched, but put off giving it a listen until recently.  Not only was I doubtful that the show would be interesting, but I’ve seen quite a few podcasts launch and then die out after only a few episodes.  So after a couple of months of seeing tweets touting the show, I finally dipped into the PPP pool.  I’m glad that I did.

Each episode has a major topic such as Data Center Switching, Enterprise MPLS, TRILL, etc.  In addition, each episode has a number of other discussions including career discussions, tech news, and the state of the industry.  Most of the time the PPP hosts are joined by an engineer whose specialty is the main topic of the show.  The content is not strictly Cisco based and the hosts have no problems taking shots at Cisco.  I’ve been impressed by the breadth of topics and guests.  I also like that the hosts are engaging and not stereotypical dry, networking nerds.

Another big issue for podcasts is sound quality.  I’ve listened to some podcasts with really great content, but shitty sound quality.  Regardless of the quality of the content, most listeners will not suffer through poor quality audio.  I’m happy to say that the sound quality of PPP is very good.

The podcasts tend to run 40 minutes to an hour in length.  The one Runt show that I have listened to clocked in at about 20 minutes.  The editing is pretty tight, which is another thing that a lot of podcasts fail at that PPP does not.

I could blather on about the Packet Pushers Podcast, but you owe it to yourself to test drive the show yourself. I was pleasantly surprised to find that the show is engaging, educational, and well produced.  I have added PPP to my weekly podcast diet.

New Feature: Cool Cisco IOS Commands

You wouldn’t know it from the quality of the end product 😉 , but researching, recording, editing, and posting video lessons can be a lot of work.  Throw in work, entertainment, and home life, and the time to create content is pretty limited.  There are many times when I get some free time, but not enough to put together a comprehensive lesson.  I’m going to utilize those shorter pieces of time to highlight some of the Cisco IOS commands that I find very useful.  These lessons will be shorter (usually less than 10 minutes) and will not include labs or quizzes.

The first of these lessons is about the ‘show interfaces counters errors’ (switching) command.

I hope that you find these lessons useful.

Cisco Flexes Muscles With Blogger

If any of you have viewed any of the Cisco related CBT Nuggets lessons, then you are probably familiar with Jeremy Cioara (his voice, if not his face).  Jeremy has run a blog for five years over at  Well, those days are coming to an end:

Well, after 5 fun years of running, Cisco “agents” have come. I was contacted by Cisco a couple weeks ago stating that violates their trademark. Being that gets 600,000 hits monthly (isn’t that amazing?!?) I thought I could at least get a box of t-shirts out of the whole deal. Unfortunately, the response went something like, “Mr. Anderson…this is a legal matter. We don’t negotiate.”

So…I have until July 4th to find a new domain name. I guess if I owned Cisco, I wouldn’t want some hoodlum posting at…so I understand the complaint.

…I just wanted a box of t-shirts out of the whole thing… :o)

Jeremy seems to be taking this is stride and I understand Cisco’s viewpoint (though they should hook Jeremy up with some nice parting gifts).  Given the slight odds (and massive cost) of winning a legal case and the fact that he probably does not want to bite one of the hands that feeds him, he’s most likely just going to move his blog.

I guess that I owe my wife some thanks.  I initially was going to call this site ‘The Cisco Gym’ and had actually created some video under that name.  My wife told me that it probably was not a good idea to do this as Cisco might step in one day and force me to change the name.  The thought of re-recording all those videos made me decide on ‘Packet Lab’.  After Cisco’s takedown of, I’m glad I made that change.

Why I Need To Edit My Videos

Dear Packet Lab,

Your mellifluous voice along with your engaging content keeps me glued to my monitor.  My friends say you use fancy editing tricks to accomplish this, but I think that you just spit wisdom with a flow that needs no enhancement.

BTW, I want you inside me.

Why thank you imaginary e-mailer who writes things that no sane human would actually type.  While it is true that I rock a mic like no other fool, even I sometimes need to use editing.

Why I Need To Edit

Why I Need To Edit

Packet Lab Finally Launching

I’m about to go have a beer…or 20.  I finally launched  It’s not perfect, but it’s good enough for the InterWebs.  :-)  The structure is built and – apart from a few minor issues/tweaks – looks and performs pretty good.  Now I can finally stop playing with Joomla, PHP, CSS, Moodle (for now), MySQL….  I can now concentrate on adding content.  I’m currently working on adding quizzes to all current lessons and will (hopefully) start adding labs sometime next week.

The War On Dynamips…Not So Much

It looks like the war on Dynamips is over before it even began.  Ivan Pepelnjak at the excellent Cisco IOS Hints and Tricks blog sets the record straight:

Let’s start with the sad fact: Dynamips’ lifeline was cut years ago when Cisco introduced the ISR routers. To run IOS on a completely different mix of hardware, Dynamips has to emulate the router’s hardware, from CPU to every single I/O device. That was “easy” (OK, doable) when Cisco used off-the-shelf components from commodity manufacturers (Motorola, AMD) who publish the detailed specs of their hardware. That tradition was broken in the ISR routers which use I/O chipsets from another manufacturer that gives you data sheets (and in-depth specs) only after signing an NDA agreement (believe me, I’ve tried and got nowhere). That’s why Dynamips supports only the 2600/3600-series and not 2800/3800-series.

The high-end routing products introduced after the 7200 series (and all switches) use customs ASICs. Obviously these are not documented outside of Cisco and thus one cannot emulate them without thorough reverse engineering.

With all these limitations in mind, it should surprise no one that you can run IOS release 15.0 in Dynamips only if you use the 7200 images (the IOS support for the x600-series routers was stopped with the release 12.4(15)T). And here comes the fatal bug in the story: IOS licensing was introduced on the ISR-G2 platforms. It is not used (yet) on the high-end boxes and will probably never be used on the 7200 platform. It should be obvious to anyone that this change in IOS deployment model has nothing to do with Dynamips (but then the story would immediately lose all its appeal).

As I stated in my previous post, I have not played with IOS version 15 yet.  I did see that there was IOS version 15 code for the 7200.  The lack of code for 3600, 3700, and 2600 just happened to be due to the end of life limitations of those platforms.  As Ivan stated, you can run Cisco IOS version 15 in Dynamips…you just need to use a 7200.

Of further interest to Dynamips devotees is that a comment that seems to have been authored by the creator of Dynamips, Christophe Fillot:

Indeed, Dynamips cannot emulate any of the platforms which run “universal images” with IOS licensing, so considering Cisco did this intentionnally is a bit strange (in my mind, this is completely unrelated, they just wanted the customers pay for the features they use). 
As you noticed, the 15.0 release just runs fine on Dynamips with a 7200 platform. 
If Cisco really wanted to break the emulation, that would be very easy to do (emulation can be detected because of inaccurate timing in the virtual machine, incomplete CPU and I/O device emulation, …), no need to look for a complicated method. 
Being the author, I obviously knew from the beginning that the program would have a limited lifetime, due to the platforms going EOL/EOS. I guess one day the 7200 will be declared EOL too. Like Stretch, I would really like that Cisco provides a full featured image running on a PC but limited in performance, or that stops working after 4 or 8 hours, for example (that’s what Xilinx, a FPGA vendor, does for evaluation purposes). Some Cisco engineers told me that technically it wouldn’t be a problem to do this, the problem is that Cisco then must have teams for the program maintenance.

Cisco At War With Dynamips?

I’ll be the first to admit that I haven’t touched IOS version 15 yet.  We aren’t utilizing it at work (outside of a small lab) and I haven’t played with it at home.  Recently I found out that Cisco has added some licensing features to the new version 15 IOS software.

I took at look at IOS version 15.0.1M1 today and there are TWENTY-FIVE different versions of this IOS available.  This includes the normal hodge-podge of IOS versions like IP Base, Advanced Services, etc.  It also included some like “AISK9-AISK9 FEAT SET FACTORY UPG FOR BUNDLES”.   I was able to download an Advanced Services IOS image for a 3845 with no problem.

The rumor that I’ve been hearing is that you will only be able to download IOS images (v15 and up) for devices that you have a Cisco contract for.  This jived with what I saw with my CCO account.  I saw IOS versions for equipment that we use, but none for devices like the 3700 and 3600 series.  This could simply be due to v15 not being available for these devices though.

One other feature of the IOS 15 images is that they require a registration key when installed on a device.  Again, I’ve not played with this version of IOS, so I cannot verify this.

So what the hell does this have to do with anything?  Well, it seems that these new restrictions may make it difficult/impossible to run IOS version 15 on Dynamips emulated routers:

With the release of IOS 15, users will need to punch a registration key into every machine running it to verify the software license. Cisco licenses its IOS feature sets at the time of purchase and when users purchase upgrade licenses at a later date. But students and professionals who have sought to experiment and practice at home — but didn’t want to pay thousands of dollars to do so — had found a loophole years ago.

As long as you had a Cisco Connection Online (CCO) account, or knew someone who would share one, you could update any router with any feature set without Cisco’s checking the license, according to users. Those same IOS software images could be used in a free and powerful Cisco IOS emulator, such as Dynamips, to give users the same experience as working on an actual Cisco router.

Using IOS images on emulated routers has always been a hazy prospect at best.  Technically, you are not allowed to run IOS images on anything except actual Cisco hardware.  Dynamips emulates Cisco routers, but does not include an IOS version.  This meant that Dynamips users had to procure the IOS software elsewhere and deal with any possible resulting legal issues.  This is why you won’t find IOS images on my site, and I will not provide you with images.

I completely understand Cisco’s desire to tighten their IOS licensing, although this article does bring up a good point:

In the enterprise space, he added, requiring a license key on every router “drastically changes the status quo” for Cisco’s biggest customers, such as large enterprises and telecom operators with thousands of routers to manage.

“Carriers have hundreds of thousands of devices, of which hundreds are under repair, replacement and upgrades at any point in time,” Ferro said. “These repairs now need licensing and re-licensing to be added to workflow. This is going to radically change the way we look at [network operations].”

Although Cisco provides software, Cisco License Manager, to transfer licenses between routers, most large enterprises are probably unaware of the changes, nor are they likely to be planning that process, Ferro said.

As it stands right now, IOS version 15 is not being used in any certification paths.  The Routing and Switching CCIE is still using version 12.4.  I don’t think that Cisco deliberately made licensing changes in order to stop the use of Dynamips.  Still, this may become an issue in the future when IOS version 15 is used more.  For right now, the effect is minimal.  Hopefully Cisco can remedy the situation for certification candidates by:

1) Creating an “academic license” version of IOS.  This is mentioned in the article.  It would have many of the features of the full IOS version, but be crippled in some way (throughput was mentioned).  This may not be something Cisco goes with for the simple fact that there doesn’t seem to be a piece of software that cannot be “un-crippled” by diligent hackers.  Of course, their registration number could be easily hacked as well.

2) Cisco currently has an in-house router emulator called IOU (IOS on Unix).  This software is used in the new Cisco Routing and Switching CCIE exam for the Troubleshooting portion.  If Cisco were to release this software (hell, they could charge for it) then they could control the IOS version that would run on it and likely kill Dynamips altogether.

For now, there’s not much to worry about.  12.4 has more than enough features for aspiring network engineers to play around with.

If you are a Facebook user, you may want to join the “Save Dynamips” Facebook group.


A Free Alternative to SecureCRT: mRemote Terminal Emulator

Since I spend a good portion of my work time working on a terminal emulator in Windows, I’ve come to appreciate the features that SecureCRT provides.  The biggest feature that I enjoy is tabbed connections.  Much like modern web browsers, SecureCRT give you the option of opening multiple terminal connections within the same window via the use of tabs.  While SecureCRT is a great program, it does require a license, which currently runs about $100.  I had searched for Window-based terminal emulators with tabbing capabilities awhile ago, but did not find anything that compared to SecureCRT – until now.

mRemote is a Windows-based application that allows you to use the very popular terminal emulator PuTTY in a tabbed environment.  Unlike SecureCRT, this application is free.

mRemote Quick Reference

mRemote Quick Reference

See my review in the following videos:

mRemote Terminal Emulator - Part 1

mRemote Terminal Emulator - Part 1

mRemote Terminal Emulator - Part 2

mRemote Terminal Emulator - Part 2

mRemote Terminal Emulator - Part 3

mRemote Terminal Emulator - Part 3

The Quick and Dirty

mRemote is an open source, terminal emulator that runs on Windows (XP and Vista). It runs on top of Putty and provides a tabbed terminal emulation experience…for free. While SecureCRT provides the same experience(and is a better option in my opinion), it costs about $100 for a license while mRemote is free. Did I mention that it’s free?

mRemote is an excellent application with a couple of flaws: it is no longer being developed and may not work with Windows 7. These limitations may make it radioactive for some Network Engineers, but the program is stable and has a few nice extra features that definitely warrant it a test drive.




mRemote download


Cisco’s TechWise TV

I’m in the process of gathering together a list of free resources related to networking.  I’ll publish them in the blog as I add them to the list, and eventually I’ll post the entire list on the Packet Lab main site.

The first of these resources is Cisco’s TechWise TV.  TechWise TV is a Cisco produced web show featuring Robb Boyd and Jimmy Ray Purser.  TechWise TV focuses on specific technology solutions (Cisco and non-Cisco) that benefit customers of all sizes and industries.  Each episode runs about 60 minutes.  The episodes are actually hosted live.  If you get on the TechWise TV mailing list you will get invites to future shows.  Obviously the benefit of the live shows is the ability to participate in the Question and Answer session.  Otherwise, the archived shows are a great way to go.

TechWise TV

You will need to register with Cisco in order to view the episodes.  If you already have a CCO account, then you should be good to go using that account.  Otherwise, you need to create a new CCO account.  I know that this is a pain, but if you don’t have a CCO account already, you really should get one anyways so that you can access the restricted areas(like IOS images) of Cisco’s website.

After logging in you will probably want to make sure your system has the required software needed to run the videos.  This meant installing Real Player (yuck) for me.  If you’re rocking a Mac or Ubuntu, then there are versions of Real Player for those platforms [here’s a tutorial on how to install Real Player on Ubuntu 9.10]

Now that you’re set up, you can dip into the episodes.  Currently there are about 55 episodes.  If you’re interested in Cisco Certification you should check out Episode 49 “Insider’s Guide to Cisco Career Certifications“.  This episode was shot at Cisco Live 2009 and touches on the various Cisco certifications.  The last chapter of the show is entitled “Gaining Hands-On Experience” and Jimmy Ray Purser pimps out Dynamips.

Insider's Guide to Cisco Career Certifications

Gaining Hands-On Experience

There are a ton of topics covered in the TechWise TV episodes so you should be able to something that interests you.

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