Category: Misc

CF Memory Cards and the Squeeze Command

Im currently upgrading some devices for a customer all over the world, nothing I didnt do before but today I ran into something suprising, at least for me. The C2811 I was going to upgrade was not having enough flash space to hold the old and the new IOS (my prefered way for upgrades) so I had to delete the old IOS to be able to upload the new one.

But after the IOS was deleted, the router did not free the flash space, this was something I was used to on older devices (C2600 for example) but not with the newer ISR routers. Quick check on google did approve what I thought, I have to use the squeeze command to free up the flash after the IOS was deleted.

I´ve found the reason after another lookup, it seems that there are 2 different file systems installed in ISR routers (guess its not for ISR2 routers but I´m not sure) a Class B and a Class C file systems. The troubleshooting guide writes the following about those two types:

Cisco 3800 series routers, Cisco 2800 series routers, and Cisco 1800 series routers use external CompactFlash (CF) memory cards to store the system image, some software feature data, and configuration files. The CF memory cards use the following file systems. The file system that is supported depends on router mode

Class B flash file system, also known as the low-end file system (LEFS)

Class C flash file system, similar to the standard DOS file system

If the router uses a Class C file system deleted files will free the space on the flash (the one I was used to) while Class B file systems require a manual intervention to free up this space. Freeing up the space on those Class B file systems is done with the squeeze command:

Router# squeeze flash:
Squeeze operation may take a while. Continue? [confirm]
squeeze in progress...
Rebuild file system directory...
Squeeze complete

If you are using a Class B flash file system, after you enter the delete flash: command, the memory space of the deleted file remains occupied, although the deleted file cannot be recovered. To reclaim the memory space occupied by a deleted file, enter the squeeze flash: command, in privileged EXEC mode.

Which Class is used on the router can be checked with the command show flash all, the Class B file system will not show any geometry and format information while the Class C file system will. Examples are shown below and are taken from the guide Troubleshooting and Maintenance: Using CompactFlash Memory Cards

Class B file system

Router# show flash: all
Partition   Size    Used      Free      Bank-Size  State          Copy
1        125184K  20390K    104793K        0K      Read/Write

System Compact Flash directory:
File  Length   Name/status
addr      fcksum  ccksum
1   6658376  c28xx-i-mz
0x40      0xE0FF  0xE0FF
2   14221136  c2800-telcoent-mz
0x6599C8  0x5C3D  0x5C3D

[20879640 bytes used, 107308776 available, 128188416 total]
125184K bytes of ATA System Compact Flash (Read/Write)

Class C file system

Router# show flash: all
-#- --length-- -----date/time------ pat
1      6658376 Mar 01 2004 04:27:46 c28xx-i-mz
25268224 bytes available (6664192 bytes used)
******** ATA Flash Card Geometry/Format Info ********
Number of Heads:      4
Number of Cylinders    490
Sectors per Cylinder   32
Sector Size            512
Total Sectors          62720
Number of FAT Sectors  31
Sectors Per Cluster    8
Number of Clusters     7796
Number of Data Sectors 62560
Base Root Sector       155
Base FAT Sector        93
Base Data Sector       187

Review of the year 2012

So its now the last day of the year 2012 and I think its time to have a little review of the year and some thoughts about the coming year.

2012 for myself was a year with a lot of changes and interesting challenges. After the move from Switzerland to Germany (which is something that most people think its crazy cause normally its the other way around) I had to start at a new company in a new country  with a totally new field of work. Its quite a difference to work for a company which is not creating any revenue with what you do (I call it internal IT) compared to a company which makes revenue out of your work. But after a year I can say, that this was the right decision to make I love my job (99% of the time, but hey nothing is perfect ;)) and the company is great. I do get a lot of support and opportunities to grow from the company and my colleagues, and this wont stop in 2013. I did start with a clear technical focus (hey Im a geek, put me into the cellar and give me some light and a computer with internet access and Im fine ;)) but it somehow shifted now during the last year. Im now doing more (technical) consulting than pure technical stuff, I even got the opportunity to develop a method to analyse the infrastructure of customers regarding their IPv6 readiness and show them a possible way to get selected services IPv6 enabled.

The probably most interesting thing is the shift of thinking, instead of thinking about systems/devices and how they connect together (aka the Network) the focus relies now on services which use the network as the underlaying system which is also another interesting point of view.

2013 will get me more into this direction since we are going to increase our consulting services and some colleagues and me are selected to develop those offers.


2012 was also a real calm year in terms of my blog, this post is only the second post for 2012! Not much I know but time and mood didn’t permit to write more 😉 I did also think about the future of this blog and what I should do with it. The conclusion out of this is to change the focus of this blog, in the past the blog was pure technical related. Trying to explain protocols and other stuff to the community, but It always took me (dunno how this is for others) a long time to write an article, check it for technical errors (you can keep grammar and spelling errors if you find them ;)). There are a lot of other blogs around which are explaining this and a lot of them are probably doing it even better than I can, I decided to write more about things I stumble upon during my projects or other things I think they might be worth sharing. Ill leave the technical explanations to people that actually do it better 🙂


Maybe one last thing. I sometimes get comments or mails from people asking me to help them with their CCIE studies. I am not going to give advice nor help, guys there are a lot of companies, blogs and mailing lists around for those things which have more actual information (hey I did pass the lab in 2008, guess how many times the lab did change during this time…). And something you really should add to your skills is to do your own research before asking to be spoon feed with information. A teacher once told me:


You don’t have to know everything, you just have to know where to find it


No one (maybe with some small exceptions) is able to know everything and if you are like 99.999% of mankind you should really make yourself comfortable with doing research by yourself, this skill will help you a lot in life (no matter if its at work or in your private life).

Ok enough of useless writings, I wish you all a happy new year and may 2013 bring you what you are looking for.

Busy time

Hi there

Its some time ago now since I did write the last post. Its not that I dont want to write, but my life did change quite a lot over the last 2-3 month.

I did decide to move from Switzerland to Germany last year in november and start at a new company here. Since december last year I do work as a Network Design Engineer at Dimension Data, one of the biggest Cisco partners in Germany. It feels now that Im on the right place to work, I do work a lot more with different technologies, protocols, boxes or whatever than before, can use my knowledge and learn a lot of new stuff or get deeper into something I did once years ago and there is still a lot of space to grow.

I also still got my flat back home until the end of the month (still in the movement process) and quite a lot of work did not really help to get time or the mood to write something 😉 I hope to find more time in the future to get up with with writing articles again 🙂

Matching Address Classes with Prefix-Lists (Followup)

This article is a follow up on the Matching Address Classes with Prefix-Lists based on the comments from killerkadoogan. I think its easier to answer the comments this way, I hope you don’t mind 🙂

Hi Pashtuk,

Under the technical definition of a CLASS C network, IE using classes. is NOT a class C network. So ‘Class C: le 32′ would also block or allow that ‘supernet’ of Class C’s, which isn’t a Class C in itself. Old-school routers (ie RIPv1) would convert the mask to /24,Class C is technically:
bits 1-3 110 + a 24 bit mask.


check out“in class c, the high order three bits are one-one-zero, the next 21 bits are the network and the last 8 bits are the local address.”so the technically correct Class C prefix list is: ge 24 le 24

you wouldn’t use that in the real world though ;)

You are right if we are talking about the old “classical” concept of Address Classes with their definition of the subnet mask.

Nonetheless the classical concept does not really matter much anymore nowadays, even though the terms Class A/B/C are still in use. Most of the time if we talk about a Class C network today a /24 subnet is thought off, no matter to which original Class the subnet belongs too.

On another occasion we can also talk about Classes in the meaning of ranges grouped into those defined classes (as used in the article).  In that case, it doesn’t matter what the typical subnet mask was, it only matters that we are able to match every subnet out of that range no matter which mask it got.

It does not have much to do with a real world approach, as a lot of the CCIE stuff I had to learn, but it belongs into the stuff a person has to know for the CCIE lab.

Cisco Press Book Giveaway – July 2011

Once more, Steve (owner of the Networking-Forum) and Cisco Press do have a free Giveaway. Check it out and good luck with the drawing 🙂

What’s going on? in association with Cisco Press is giving away 5 free copies of IPv6 for Enterprise Networks.

This is a monthly event so check back next month if you already have the book above.

How are the winners chosen?

It’s simple, add yourself to the forum’s ‘Cisco Press Book Giveaway’ group. Yep, that’s it.

1) Go to your User Control Panel
2) Select the ‘Usergroups’ option on the left
3) Select the ‘Cisco Press Book Giveaway’ radio button
4) Make sure the drop-down menu says ‘Join selected’ and hit the ‘Submit’ button

You should receive an email confirming that you’ve been added. Or you can view the members of the group to ensure your username is on the list.

Towards the end of the month, the forum staff will close the group and randomly select the winners. The winners will be announced in this thread and they will have a few days to provide their shipping information.

Other details

  • Neither (Amoeba Solutions LLC) nor Cisco Press is responsible for issues with this giveaway.
  • There will be mistakes made. Don’t get mad or sue. Simply enter next month’s giveaway.
  • The rules and or details may change at any time.


Any news/updates/changes will be posted here. CCNA Specialization Scholarship

After the last Scholarship in September 2010,  the got (check here) a new one, now offering a Scholarship for a CCNA Specialization Track, good luck 🙂

What’s going on? is offering a scholarship to one person who would like to earn a Cisco Certified Network Associate specialization certification (CCNA Security, CCNA SP Operations, CCNA Voice, or CCNA Wireless). The scholarship will provide study material, a separate forum specifically dedicated to the candidate for his or her use during their studies with feedback from the site’s members, and reimbursement of the exam fees after they pass their exam.

The Specializations/Exams

  • CCNA Security – Implementing Cisco IOS Network Security (640-553)
  • CCNA SP Operations – Supporting Cisco Service Provider IP NGN Operations (640-760)
  • CCNA Voice – Administering Cisco Voice and Unified Communications (640-461)
  • CCNA Wireless – Implementing Cisco Unified Wireless Network Essentials (640-721)

How is the recipient chosen?

To qualify for the scholarship, candidates will need to write an essay about why they want to earn their CCNA specialization certification and why they make a good candidate for the scholarship. All essays must be received by May 18th, 2011 and posted in this thread. The essays will be judged by our staff and a few prominent members. The recipient will be announced in this thread and notified via a site private message on May 25th, 2011.

The Judges

What is expected of the recipient?

The recipient of the CCNA Specialization Scholarship is expected to do the following:

  • Keep the community informed of their progress by participating in the dedicated forum.
  • Write 3 750+ word blog posts on a topic of their choice.

Other details

  • CiscoPress is sponsoring the scholarship by providing books. Thanks to them for supporting the site and the cause.
  • The recipient has 3 months to pass their exam after being chosen.
  • The recipient must have an active CCNA to qualify for the scholarship.
  • Proof of the passed exam(s) must be provided to receive reimbursement.
  • A picture of the candidate’s face and dated score sheet will need to be posted on the site or sent to Steve.
  • Reimbursement for passed exam fees will be made via or check and will not exceed $250 USD.
  • The recipient can not be reimbursed by another party for the same exam.
  • The rules and or details of the scholarship may change at any time.

Rant: Job Postings and Comments

Well, its some time ago since my last post and this will also be a new kind of post as it looks like. I usually do try to keep my personal opinion out of my blog posts, but this is something that does bother me since some time now.
Even though I’m not actively searching for a new job, I’m a member of quite some groups on Linkedin from which I do get quite some job postings. I really sometimes don’t get it why people do write posts/comments like it is happening. Its basically on both sides, the recruiters and the job seekers.



I often see posts like “I need a CCIE!! please send your resume to” There are quite some variations of that type, but in the end its all the same.
Dear recruiter, please do provide some more information on what kind of position you are talking about, where it is located and (very important IMHO) if the company is sponsoring people from outside the country the job is located in. In the end, you earn money with finding fitting people for the open positions you do have, so why don’t you do write some more about it? Another benefit of more information you (probably) will get less messages from people that don’t fit into the requirements or do live in the wrong part of the world, which leads to less time to invest to write back.


Job Seekers

Most of the time I see comments on job postings like “pls check my profile”.
Guys, do you really think its enough? In the End you want to have a new job, so do invest some time and write a message to the recruiter with more than just “pls check my profile”.. Write a short notice about what you’re currently doing and that you’re interested in the job. DO something for it..


In my opinion, this should be something very basic for both sides. How much time does it take, to be more specific or to write a bit more. In the end both sides are interested to get that up and running, one wants to find people and the other ones try to find a new job/opportunity/challenge.

Its only my 2cent about this thingie and I might have some new “friends” now, but its how I see it .-)