ChrisWelsh 2014-09-03.png

Welcome to RedNectar’s blog. My name is Chris Welsh and I am a professional computer networking instructor – Cisco, TCP/IP, Data Centre – ie general networking technologies.

The RedNectar tag has some history.  Some Australians who went to school between 1983 and 1988 might remember the Aussie MicroBee computer.  Or “the Bee” as we affectionately called it.

I wrote some software for the Bee – and marketed it through my company name “Nectar Software” (Nectar for the Bee of course).

I don’t do software any more, but my company has kept the Nectar in the form of “Nectar Network Knowledge”.  http://www.nnk.com.au

When looking for a username one day, I tried “nectar”.  The response I got was that “nectar was too short.  Why not try blue_nectar or nectar_123?”  I thought about that, and decided that Red_Nectar had a much better ring to it than blue_nectar, so now I use the RedNectar tag (or a variation thereof) wherever I can – including this site.  You can follow me on twitter @rednectarchris and blame me for any wikipedia edits by Rednectar.chris. You can also find me on Google+.


78 Responses to About

  1. anderson.reloaded says:


    I came across your blog while searching for an answer related to Dynamips. Excellent blog you have!. Need your suggestion regarding an observation that Dynamips is crashing when doing simple file transfer using SCP between real host connected to VirtualBox VM, which is part of GNS3 network. To simplify the problem, lets say we have a GNS3 network consisting of VirtualBox VMs connected through Ethernet switch, which is also connected to external real network via trunk port. When we are performing simple file transfer from external computer to VM, the transfer begins and Dynamips on the Host crashes causing the network to become disconnected to real network.

    Are there any limitations of using Dynamips for simple file transfers ? Or are we missing something in its configuration ?

    • I can’t give you a definitive answer, but to me the idea of pushing file transfers through Dynamips is probably asking a bit much. More on that soon, but my first thought is “Why are you doing SCP though GNS3?”. Your Virtual Box VM should be able to connect directly to the outside network and you could then bypass GNS3/Dynamips altogether.

      But that aside, remember Dynamips is an emulator, emulating the MIPS processor and thus giving the GNS3 developers the ability to build emulated network devices based on that MIPS processor – ie Cicso 7200, 2600 and a few others – including Cisco 3750 router with an Ethernet switch module. Since you mention that Dynamips is crashing, I’ll assume that this is what you are using as the “Ethernet switch” you mentioned. The GNS3 folk also then decided to add a couple of other emulators and simulator into the environment, such as QEMU and VirtualBox, but the magic GNS3 is that it gets these devices to talk to each other. How? By using very simple UDP tunnels.

      What GNS3 does is create virtual interfaces that are nothing but an IP address and UDP port number, so when you begin an SCP transfer, TCP segment get squashed inside UDP datagrams – and this is going to create packets larger than 1500 bytes, and when you put a 1500 byte payload into a UDP datagram, well something has to happen. To be honest, I don’t know how GNS3/Dynamips handles larger packets (remember it was designed to carry RIP and OSPF etc, NOT TCP) although I suspect the Virtual Box VMs would be smart enough to figure out a smaller MTU.

      Now the point of this is really that I think you are pushing the limits of what can be expected from an emulator that was designed to carry routing protocol packets between routers, not TCP based file transfers. If the file transfer has to be done through GNS3 rather than directly to the Virtual Box VM, my advice would be to reduce the MTU on the device that is on the external network to begin with, and on the Virtual Box VM too. And if that fails, perhaps try a different file transfer method, like FTP or TFTP.

      • anderson.reloaded says:

        Hi Chris,

        Thank you for your response! We shall explore alternate means of carrying file transfer external to GNS3. GNS3 is powerful but has its pros and cons as highlighted in your response. Thank you once again. Do we have alternate means of creating VLANs and networks between VirtualBox VMs on single host and across different hosts ?

  2. Nuwan Liyanage says:

    Hi Chris ,
    1) what are the limitation when practice CCNP switch lab on GNS3 workbench ? i heard some commands and some features not support in workbench.
    2 ) And i heard CiscoVirL is good for switching practice. is there anyway we can import CiscoVirl to GNS3 workbench . i imported Cisco VIRL IOSv into GNS3 VM but feel it use more CPU resources compare with workbench .
    is there any benefit of this method compare with workbench for advanced Cisco lab ( CCNP, CCIE )?
    Thank you

    • Hi,
      Sorry so slow to reply. But you are correct in that anything beyond simple VLAN operation and PVST is pretty much impossible with the GNS3 based on Cisco IOS which is what I used in the GNS3 Workbench. Life got in the road of me ever upgrading it to the next version of GNS3 which supports IOU which has some better switching features – can’t say if they are exactly the same as VIRL. And I certainly never tried to get any import function from VIRL working.
      Sorry I can’t give you much more help.

  3. Amit S. says:

    Hi Chris,

    I would like to thank you sooooo much for such a awesome ACI blogs, I found things here which are not well documented even in Cisco Docs. You are surely doing a great job. I wish to find a subscriber button on your website and keep up with your great work.



  4. spidernik84 says:

    Hello Chris,

    Thank you for your blog and your superb ACI articles.
    I know you have already replied to the many requests to complete the series, so I won’t be yet-another-guy asking the same thing 😀
    Have you thought about publishing your series as a book on a platform such as Leanpub? This way you could monetize and get constant input from your users.
    I think your work is invaluable and should be promoted more. The official ACI documentation is just too dry, scattered and detailed (although admittedly very complete) for a first approach to the platform, and your work (together with Adam Raffe’s other excellent series) is the best start.
    Thanks again!

    • Alexander,
      Sorry for the slow reply – yes I’ve had requests from publishers to write a book. I’d love to, but I don’t seem to have the time to even keep my blog up to date, let alone write a book!
      And thanks for the kind comments!


    Hi first of all i would like to thank you for such a wonderful post..its very awesome way to study…
    i cant tell you how helpful ACI post for me and for my career..god bless you every-moment of life.

  6. pmales says:

    Hello Chris,
    Great blog, I just finished reading your ACI tutorial and can’t thank you enough. It really helped me out. I was wondering if you you are still thinking about finishing out the tutorial? Thank you, now to go back and read it again now that i have a better understanding.

    Again, thank you very much.


    • Hi Phil,
      Thanks for the kind comments. I hope the tutorial helped!
      Finding time to complete the series has been a challenge, but I do have some more material almost ready to go so I’ll try and get that up soon.. When I get to the Layer2/3 tutorial, it is going to be very similar to the inland management articles I did about Christmas time, so you might glean some extra knowledge by going through them.
      Chris (RedNectar)

      • Ama says:

        Hi Chris,
        I would like to ask you to finish ACI Tutorial – that is fantastic !!
        Please find some time for it. Many of us will be really grateful !
        Best luck ! You’re awesome !

      • Thanks for your kind comments – I really must get that done

  7. Roberto says:

    I found them Chris, Thank you again!

  8. Roberto says:

    Hello Chris, First of all thank you for doing this; its great help. I was wondering if you have the single labs instructions on text as I already have GNS3 up and running; I have done a few labs, I have read many books, almost finishing watching the training videos. I just want a readiness practice test lab. Is that possible? A zip folder will do 😉 If not possible, thats ok too man. Thank you!

    Kind regards,

  9. Eric says:

    Hi Chris

    thanks for sharing the info
    I was trying to set up the gns3 work bench in the onepk virtual machine I got….and am having difficulty with python3, gns3server. is there an updated script I can use?

    • Hi Eric,
      I’m afraid I haven’t updated the GNS3 install script for some time – it became too much of a moving target to try and keep up to date once the migration to v1.4 began

      So at the moment, I can’t help you – sorry about that. I might try and update the script when v1.4 is released


  10. Vic says:

    Hi Chris,

    Couldn’t post this in the respective VMWare blog section, I guess it’s closed for new comments. Anyway, just wanted to say thank you for sharing your knowledge, it really helped me. I’m sure I’ll be back on your page soon.


  11. sh0ckabuku says:


    I just finished creating a QEMU from the freebsd image, patch, and junos os file. The instructions were perfect and it was a lot of fun. Just wanted to say thanks buddy.


  12. Chris,

    Wow! What a great great setup you have made with Workbench 8.7! I was trying to build my own on Mint and immediately ran into various issues that I just did not want to spend time trying to solve. Even without issues I still would not have the great labs and scenarios which are just invaluable for someone like me trying to get their first CCNA cert.

    Entry level question here, but I’m still starting out so bear with me. The ICND1 IPv4 DHCP & NAPT Exercise is broken. I could not get regular ICMP ping to work from PC1 to PC3. The kicker is that the Completed Snapshot (i.e. the answer key) doesn’t work either. Been pulling my hair trying to figure why ICMP’s are not coming out s0/0 on R1.

    My enduring thanks for the work and reply!
    Paul N.

    • Ah=ha. You’ve found the secret Challenge Question!!! :-))

      Seriously though, I’ll have a look at it. Thanks for pointing it out.

      [Edit:] Just tested on my test VM. I loaded snapshot 9 and started the routers, made sure they were fully booted and then started vpcs, and entered the load check-answer command. All worked well. I even did an extra ping at the end (PC1 to PC3) to be sure.

      VPCS[1]> load check-answer
      Executing the file "check-answer"
      *************** Checking Answer ******************
      Obtaining dhcp addressess for VPC1 & VPC2.  You should see something like:
      DORA IP GW
      DORA IP GW
      Should now see ip addresses assigned to VPCS1 and VPCS2
      NAME   IP/MASK              GATEWAY           MAC                DNS
      VPCS1          00:50:79:66:68:00
      VPCS2          00:50:79:66:68:01
      VPCS3             00:50:79:66:68:02  
      VPCS4             00:50:79:66:68:03  
      VPCS5             00:50:79:66:68:04  
      VPCS6             00:50:79:66:68:05  
      VPCS7             00:50:79:66:68:06  
      VPCS8             00:50:79:66:68:07  
      VPCS9             00:50:79:66:68:08  
      Testing ICMP reachability to PC3. You should see ping replies like: icmp_seq=x ttl=62 time=xx.xxx ms
    icmp_seq=1 ttl=62 time=20.697 ms icmp_seq=2 ttl=62 time=21.877 ms icmp_seq=3 ttl=62 time=14.869 ms icmp_seq=4 ttl=62 time=15.244 ms icmp_seq=5 ttl=62 time=20.903 ms
      Testing DNS has been set correctly. You should see replies like:
      pc3.acme.com resolved to icmp_seq=x ttl=62 time=xx.xxx ms
      pc3.acme.com resolved to icmp_seq=1 ttl=62 time=20.875 ms icmp_seq=2 ttl=62 time=27.428 ms
      Testing TCP reachability to PC3. You should a ping reply like:
      Connect   80@ seq=x ttl=62 time=xx.xxx ms
      SendData  80@ seq=x ttl=62 time=xx.xxx ms
      Close     80@ seq=x ttl=62 time=xx.xxx ms
      Connect   80@ seq=1 ttl=62 time=20.541 ms
      SendData  80@ seq=1 ttl=62 time=19.980 ms
      Close     80@ seq=1 ttl=62 time=31.233 ms
      Test completed, scroll back to see how well you scored.
      To test your answer again, type the command:
      load check-answer
      VPCS[2]> 1
      VPCS[1]> ping icmp_seq=1 ttl=62 time=18.984 ms icmp_seq=2 ttl=62 time=18.145 ms icmp_seq=3 ttl=62 time=15.204 ms icmp_seq=4 ttl=62 time=18.429 ms icmp_seq=5 ttl=62 time=17.831 ms

      The only thing I can think of is that IF you started the VPCS program BEFORE you had the configs completed and the DHCP server operational, you may have missed out on getting a DHCP address on VPC#1 and/or VPC#2.

      So check that your VPCs do indeed have an IP address before you ping.
      show ip all
      will show you all IP addresses.

      • pjneder says:


        Hmm, there must be something else goofy in my environment. I started everything up clean from snapshot 9. Here is the (truncated) output from vpcs showing assigned addresses and the failure.

        Checking Answer
        Obtaining dhcp address for VPC1
        DORA IP GW

        Obtaining dhcp address for VPC2
        DORA IP GW

        Should see ip addresses assigned to VPCS1 and VPCS2

        VPCS1 00:50:79:66:68:00
        VPCS2 00:50:79:66:68:01
        VPCS3 00:50:79:66:68:02
        VPCS4 00:50:79:66:68:03
        VPCS5 00:50:79:66:68:04
        VPCS6 00:50:79:66:68:05
        VPCS7 00:50:79:66:68:06
        VPCS8 00:50:79:66:68:07
        VPCS9 00:50:79:66:68:08

        Testing ICMP reachability to PC3 – should see ping replies icmp_seq=1 timeout icmp_seq=2 timeout icmp_seq=3 timeout icmp_seq=4 timeout icmp_seq=5 timeout

        R1 shows the dhcp binding. I am running a slightly different version of IOS since this is what I had available. I ran your update-image script on the workbench before I started. Everything else is default except for RAM and CPUs assigned to the VM. All other labs have behaved perfectly so far.

        Acme1>sh ver
        Cisco IOS Software, 3700 Software (C3725-ADVENTERPRISEK9-M), Version 12.4(15)T14, RELEASE SOFTWARE (fc2)

        The important thing to me is that there is not something lurking in here that will catch me out on other labs/scenarios and cause me to mis-learn a topic.

        Again my deep appreciation for your great work here!

      • It shouldn’t be an IOS problem. I’m stumped!

      • pjneder says:

        Well…empirical evidence trumps us. Tried the 124-15.T8 image and it works. Can’t seem to get my hands on the T10 image. Lesson learned. Either I have a bad image or something with T14 doesn’t work exactly correct in this environment.

  13. Glen Sonnenberg says:


    I downloaded your GNS-Workbench image and imported it to an ESX server at work. I want to be able to create/clone a bunch of different virtual network topologies which will interact with our test lab network. I’m having something strange happen when I try and connect a virtual router to the routers in the lab. I can create a virtual router and connect it to a cloud in GNS3. I can configure the interface on the router with DHCP and it will get an IP address from the DHCP server on the network the Host VM is connected to. However, I can’t ping anything other than the IP of the interface itself. I can’t ping the address of the Host VM itself or the default gateway for the network it’s connected to. Have you heard of any problems with using the VM image on an ESX server? Any thoughts on what to do? I figured that once I had the IP address from the DHCP server that would mean communication was working. Any help would be appreciated. Thanks.

    Glen Sonnenberg
    Packet Design

  14. Element Kuo says:

    Dear Chris

    Sorry to bother you. I had read your book to understand about GNS3 and to build my labs for studying about Cisco skill. Recently, I would like to build ASA lab to study CCNa-Security but I meet some problem. Please help me thank you.

    My Lab Environment is
    Physical Computer-OS: Windows 2012 R2 Std Server
    1. Run VMware Workstation 10.x version.
    Virtual Machine 1 in VMware Workstation.
    1.Ubuntu 14.04 LTS Desktop version
    2.Installed GNS3 v0.8.6 from PPA including Dynamips, VPCS, Qemu…)
    3.Cisco IOS:c7200-advipservicesk9-mz.150-1.M.bin
    4.Cisco IOS:C3725-adventerprisek9-mz.124.15.T10.IMAGE.BIN
    5.ASA Image: ASA 842 version
    6.Virtual Machine 1’s IP Address is world IP)

    Virtual Machine 2 in VMware Workstation
    1.Windows 7 64 bit
    2.would like to using telnet to connect Router and ASA’s console port.
    3.Virtual Machine 2’s IP Address is World IP)

    Explain environment what I need
    1.I would like to connect ASA and Router_7200’s console port from VM2(Win7) by telnet software.(for example telnet 2101(Router) and telnet 3001(ASA)

    My Configuration in GNS3 of Virtual Machine 1
    1.GNS3 Configuration: Tools Bars in GNS3 –>Edit–>Preferences–>Dynamips–>Hypervisor Manager–> IP/host binding–>
    2.GNS3 Configuration:Tools Bars in GNS3 –>Edit–>Preferences–>Qemu–>General Settings–> Show QemuWrapper Advanced Options–>IP/host binding–>

    I try to implement my topology in GNS3
    1.Topology: before save I drop and drag the topology in below
    Physical (NIC) Bridge VM1(e1) Cloud (e1) (e1) ASA (e0) (F0/0) Router_7200
    Physical (NIC) Bridge VM2(e1)
    2.I start Router_7200 and ASA that is running good and I can connect Router_7200 and ASA’s console from VM2(Win7) by telnet software (for example telnet 192.168..119.139 2101(Router) and telnet 3001(ASA))
    3.Everything is running in good state

    I shut Router_7200 and ASA and save the project properly and re-open this project again. some problem happened.
    1.I start Router_7200 and ASA that is running good and I can connect Router_7200’s console port but I can not connect ASA’s console from VM2(Win7) by telnet software (for example telnet 192.168..119.139 2101(Router) and telnet 3001(ASA))
    2.I check ASA’s console port(TCP Number) that is from 3001 change to 3004 automatically.
    3.I can connect ASA’s console port from VM1(Ubuntu) by term software(I can connect 3004 but can’t connect 3004)
    4.I can not connect ASA’s console port from VM2(Win7) by term software also(telnet 3004)

    My question is
    1.Why I can connect to ASA console from VM2(Win7) before saving the project? but I can’t connect it again from VM2(Win7) after saving project and re-open it?
    2.Why ASA console port number will change automatically after saving project?
    3.Is my configuration correct?
    4.How can I connect to ASA console from VM2(Win7) even if saving the project and re-open it.
    5.How can I solve the problem?

    Thank you for your answering


  15. David Smith says:

    Hi Chris,
    Firstly this is a great site with some fantastically written tutorials so thank you.
    I recently read your tutorial about VMWare Interfaces and it has helped me a lot. However I am still having some minor issues and wondered if that was something you would be able to offer some assistance with? If so where / how is the best way to get that over to you? Wasn’t sure this was the best place, and the tutorial post has been closed now.
    Thanks in advance

  16. HaveF HaveF says:

    Hi, Chris,

    Sorry to bother you with a question about ethernet redundancy.

    My boss want to set up ethernet redundancy for our company network. After a quick search, I find STP(and other variant) and trunking maybe my choice, then I want to look their performance and internal principle about them, so I search network simulation. Finally, I find GNS3, but I haven’t try it yet.

    1. do you suggest me to do this?(keyword will be fine, I will search them then)

    2. about competitor of GNS3, can you suggest some other tools(keyword will be fine, I will search them then), than I can make a comparison.

    Sorry to bother, thanks again!

    • In 2014 for normal office switch redundancy there is no other proven technology other than spanning tree. Spanning tree has several forms.

      IEEE 802.1D-2004 which includes rapid spanning tree (RSTP)
      IEEE 802.1Q-2005 which adds Multiple Spanning Trees (MST or MSTP) to RSTP

      The main competitor to the standards based approach is Cisco’s proprietary PVST/PVST+ (Per VLAN STP/Per VLAN STP over 802.1Q) which is the default spanning tree method for all Cisco Catalyst switches (Nexus switches use MSTP by default). Cisco also support a proprietary Rapid Per VLAN Spanning Tree (RPVSTP) on most switches.

      On some Cisco switches (that don’t support spanning-tree mode mst) I don’t believe you can turn off the proprietary PVST/PVST+

      Each case should be looked at specifically, but as a general guide:
      For a small operation (fewer that 10 VLANs) I would recommend using MST with all switches using the CST – in other words a single standards based spanning tree
      For a larger operation (more that 10 VLANs) I would recommend using MST with two instances of spanning tree – put half the VLANs in one spanning tree, half in the other.

      More modern redundancy methods that “compete” with spanning tree are:

      IEEE 802.1aq-2012 – Shortest Path Bridging (compatible with MTP I believe – need to check)
      TRILL (Transparent Interconnect of Lots of Links) – beware Brocade’s implementation is incompatible with Cisco’s implementation
      Fabric Path (Cisco proprietary implementation of TRILL plus extras)

      Re: GNS3 competitors
      Boson has a simulator but it doesn’t use Cisco IOS, so what you see may match what you see on the exam, but not necessarily what you see in real life
      Cisco is coming out with CML (previously known as VIRL). Hope you have lots of CPU power and RAM

      That’s all that I know of


      • HaveF HaveF says:

        Hi, Chris, many thanks for your typing these words, you are just a great walking encyclopedia.

        Maybe I mislead you about my purpose. The aim of ethernet redundancy is to make sure our company’s control system as steady as we can.
        But your words gives me a lot of references to look at.

        Thanks again!

  17. daniel says:

    hello chris,
    im a great fan of you GNS workbench app.
    is there a guide on your blog how can i integrate an Cisco ASA image?
    i tried many things from the gns forum or 7200emu forum, but nothing works.
    thank you for a hint

  18. Jim Parens says:

    Good evening Chris, in your ICND2 folder in Workbench, you have an ACL lab. There is a tab that executes to check to see if VPC1/2 is accessing the servers properly via the ACL. Seems like it runs a script. How can I restart this script if I am checking my ACLs or trying to troubleshoot my ACLs? I wasn’t able to do anything after I ran the script once. Any help would be great!


    • Jim,

      1. Re GNS3 v1.0 – yes I did sign up and am busy trying to put some suggestions together for Jeremy. As for creating a new WorkBench for v1.0 – I’ll say “probably”

      2. The ACL lab in GNS3WB 5.8 is setup so that when you finish running the “Check-Answer” script, you can just type “quit” to quit VPCS, and it’s good to run a second time (it will keep count of how many times you’ve run it too)



  19. Jim Parens says:

    Hello Chris,

    GNS3.NET will have a new version of GNS next month that will incorporate switching. Did you sign up for this new version, and more importantly, will you create a new Workbench appliance with this new version of GN3?

    I hope so. Thanks a lot!

  20. Jim Parens says:

    Hello Chris, I worked out the previous lab with the 6 RIP routers. All is good. I just did the “Acme3Router” lab. I configured Acme3 router with RIP, no up subnet-zero and IPs. All is working when I ping from VPC1 to VPC3, and vice versa. Could you check my “router rip” and “sho ip route” results and let me know if I met the lab requirement? Thanks!

    router rip
    version 2
    no auto-summary

    Acme3#sho ip route
    Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP
    D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
    N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
    E1 – OSPF external type 1, E2 – OSPF external type 2
    i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
    ia – IS-IS inter area, * – candidate default, U – per-user static route
    o – ODR, P – periodic downloaded static route

    Gateway of last resort is not set

    R [120/2] via, 00:00:18, Serial0/1
    R [120/1] via, 00:00:18, Serial0/1
    R [120/1] via, 00:00:18, Serial0/1 is subnetted, 2 subnets
    C is directly connected, FastEthernet0/0
    C is directly connected, Serial0/1

  21. Jim Parens says:

    Hello Chris,

    Love your Workbench VM and always use it to study. I am currently doing the “6RoutersRIP_TS” lab. In the instructions, our goal is to not have”all router have a complete routing table with no hop counts larger than 3.”. How can I check if the hop count is a max of 3? When I do a traceroute from VPC6 to VPC1, I get five hop counts. Is my solution still wrong? Thanks!

    VPCS[6]> tracert
    traceroute to, 64 hops max, press Ctrl+C to stop
    1 5.753 ms 2.837 ms 2.335 ms
    2 5.470 ms 3.061 ms 2.949 ms
    3 13.099 ms 13.004 ms 10.274 ms
    4 16.936 ms 12.246 ms 13.727 ms
    5 16.427 ms 20.288 ms 15.137 ms

    • Hi Jim.

      Your trace is working as expected – the count of 5 comes from the fact that there is one hop from VPC6 to R6, and another hop between R1 and VPC1.

      The two main troubleshooting commands you will want to use on the router are:
      show ip protocols
      show ip route

      It is the show ip route that will show you the hop counts inside brackets, as highlighted below from a show ip route command issued on R6

      show ip route
      Gateway of last resort is not set
      R [120/2] via, 00:00:21, Serial0/0
      R [120/1] via, 00:00:18, FastEthernet0/0
  is subnetted, 9 subnets
      C is directly connected, FastEthernet0/1
      C is directly connected, FastEthernet0/0
      R [120/1] via, 00:00:18, FastEthernet0/0
      R [120/2] via, 00:00:21, Serial0/0
      R [120/1] via, 00:00:21, Serial0/0
      R [120/1] via, 00:00:21, Serial0/0
      R [120/2] via, 00:00:18, FastEthernet0/0
      R [120/2] via, 00:00:18, FastEthernet0/0
      R [120/3] via, 00:00:21, Serial0/0
                          [120/3] via, 00:00:18, FastEthernet0/0
      C is directly connected, Serial0/0

      As you can see, the largest hop count shown is 3

      • Jim Parens says:

        Thanks Chris. That is what I was looking for. I guess my only issue is, I issued the ‘no auto-summary” on all the routers’ rip config, and also switched it to version 2. But when I begin to enter the different 172.16.XX.0 networks, the routers still summarize this to I do not think that is the expected behavior. Is there something I am missing?

        Thanks again!

  22. SNap says:

    Chris, i’m running GNS3 in winXP. After I’m starting Virtualbox devices, GNS3 disappear but virualbox devices still running. If i’m starting GNS3 again, it show blank page. What is the solution to this issue ?
    sorry if my explanation did’nt clear. thanks

  23. rednectar says:

    Mohammed – I’d love to help but after spending 10mins trying to draw a diagram of what you have I gave up. Sorry.

    • Thanks alot, Mr. Chris, I really appreciate ur care, the thing was I had 2 optical fiber megaplexes ( a device like the optimux as a think). The input to the megaplex could be pbx lines or data lines of rj-45, and the output is optical fiber line, that optical fiber is received by another megaplex that converts data travelling along that optical fiber cable to the original pbx and data lines again. that megaplex device uses TDMA. to send multiple data lines through the megaplex a hub is used for sure, with that megaplex connected to one of the hub ports as the other data lines connected to the hub as well. in my case there were one data line to be sent, so I connected that data line directly to the UTP port of the megaplex without using the hub,,, so no connection established !!
      the data line I tried to connect to the megaplex,, was a connection to a PC uses the old 3com Etherlink xl LAN card,, when tried to connect another PC instead of that old one, the connection was successful,,, well, at ;last; I put the hub in between the old PC and megaplex,,, and the connection was OK then !! I just went to the conclusion that 3com old LAN can’t get connected to a megaplex directly !!!!!!!!!!!!!!
      but, thank you, sir, for time and care, I really appreciated 🙂

  24. Hi, Red, I just wanna to ask a question, I have a windows NT 4.0 PC, used to monitor a system 2 km away, and so, I got that PC’s NIC connected to a TDMA megaplex, by an ordinary straight RJ45 and by turn the megaplex outputs the data after gettn TDMAed through an optical fiber to an identical megaplex in that remote station which is connected, I mean the megaplex, to an internal LAN containing an identical windows NT PC, that LAN I have mentioned is an old token ring network with a hub as a member, from that hub an RJ cable connected to the megaplex of the station, well, I couldn’t ping the station, I mean that PC of the remote station, through my monitor PC !! but,when I replaced that monitor PC with my win7 laptop I was able to ping the station,, I tried to ping my monitor winNT PC with my laptop, through a cross over cable, I was able to get replies,, but when pinged the laptop using the monitor PC I got my requests time outed !!!! I don’t know how can a PC ping another one, but that other one can’t ping that PC 😦 ”’ the problem is not just pinging but that the software of the monitor PC can’t then connect to the station,,, please help, I wanna that monitor PC sees the station !!

  25. GregV says:

    Hi Chris, I just wanted to say thank you for putting together this bundled vm. It’s fantastic to have everything in one place, nicely organized and simple to use. Beats my old rack full of test routers any day!

  26. THomas Munn says:

    I did try downloading the vmdk files, converted to ‘ovf’ and then ran under virtualbox. No qemu binary anywhere, pix images don’t work.

    Nothing I could do would get gns3 to work. I get fine interfaces, and I also get fine ubuntu. Previous verison with same process works great.

    Any Ideas? I searched the entire filesystem for a qemu something binary, NOTHING on entire system.


    • rednectar says:

      I didn’t set up Qemu/Pemu/PIX on the distribution – but that shouldn’t stop the main emulator (dynamips) from working within GNS3 – did you try running the VMWare version using VMWare Player?

  27. Mike Gage says:

    hahaha…that definitely looks like it will do the trick. It is gonna take me a couple of days to get all of those files downloaded on my hotel wi-fi, but I’m positive that will fix the problem…thanks again.

  28. Mike Gage says:

    Chris, I am trying to load the GNS Workbench on my laptop, but having been having problems. I downloaded the file from sourceforge.net, and I also have loaded VMWare Player on my laptop. I am following the directions here on the website, but everytime that I copy the workbench file into the Virtual Machine folder (it is showing up as a .vmdk file, not a .vmx file), I get the error that it is not a valid Win32 application when I try to open it up. Any ideas?
    – Mike Gage

  29. Rich Glauser says:

    I am having issues with an mpls network I have set up in GNS3. I followed the configuration examples and guide you assisted with in the GNS3 forum. The issue I am having is my ce routers establish a bgp neighbor with the pe router. In the pe router with sh ip bgp vpnv4 all I can see all the routes from both ce routers however they are not being populated to the ce routers. I cannot ping across my network. I am using 3700 series routers with advipservicesk9 12.4 as the os. Any insight would be greatly appreciated.

    Sorry about taking this off topic.

    • rednectar says:

      Sounds like a a redistribution problem. If you want to send me your configs (to my gmail account for rednectar.chris) I’ll try and have a look (your topology.net and the configs directory).

  30. Roger Perkin says:

    I just want to say a big Thank You for developing GNS3 Workbench, I have been a user for a long time and just downloaded your latest version. It is awesome. To recognise you for your efforts I have done a great blog post on my CCIE Blog site http://www.rogerperkin.co.uk/ccie/index.php/gns3/gns3-workbench-awesome/ If you google GNS3 Workbench is awesome you will see it come up!
    Anyway I wonder if you could put a link back to my site http://www.rogerperkin.co.uk/ccie with the title Roger’s CCIE Blog in your Blogroll?
    I am pursuing my CCIE and blogging about CCIE related topics and also other random network stuff I come across – like a wireless Console cable! Watch the blog for that one soon.

    I look forward to hearing from you and Thanks again

  31. rednectar says:


    I started writing the script, didn’t get it working so removed it from the distro – but forgot to remove the link in the /opt/GNS3/IOS directory.

    I’ll post it when I get it working.

    Sorry about that


  32. Dis Course says:

    No script for GNS3 Vault IOS firmware change?
    script to change GNS3 Vault firmware image -> /opt/GNS3/READMEs & Scripts/script to change GNS3 Vault firmware image

    The file “script to change GNS3 Vault firmware image” does not exist in the directory “/opt/GNS3/READMEs & Scripts”

  33. Doug Hecht says:

    Chris, Thank you for the work that you did with VMware and GNS3. Allot time was put into that and it is really a very valuable tool. However, my problem is that I cannot get a copy of c3725-adventerprisek9-mz.124-15.T10.bin to make it work and your scripts that will allow me to use any IOS are a bit cumbersome. Any ideas?

    • rednectar says:

      Until Cisco publicly announce that they will allow users to use IOS on simulated platforms without breaking the licence agreement, I have no way of publicly helping you. Sorry about that.

  34. Adrian says:

    Hi Chris, are you planning a release for GNS3 0.74? I still seem to have issues emulating an ASA 8.0.

  35. KishoreKannan says:

    Hi Chris,
    For your information SecureCRT released a new updated version for Linux ( Ubuntu 10.x 32 & 64 bit, RHEL 5.5 32 & 64 bit), You are using Konsole as a terminal emulator for tabbed sessions and it needs more space and more packages that are not needed for GNS3, but this securecrt has got more features and requires less space

  36. garry says:

    Hi Chris,

    Sorry but am a little confused about something. I’ve got VMWorkstation running on Win7 and see in one of your exercises “Your Windows PC” … Can you point me to where I can get that working please? I’ve got a “loopback on my win7” but how do I get it into this VM excercise?

    • rednectar says:

      This is a little confusing I admit – Perhaps one day I’ll get around to writing a bit more detail, but for the quick answer:
      1. Firstly, as you assumed “Your PC” is the host PC, – your Windows PC as apposed to your “Ubuntu Virtual PC”
      2. You don’t need a loopback (as you would if you were running GNS3 directly on your Windows PC) – what you need is a way of connecting your Virtual PC’s interface to your Windows PC’s interface.
      3. To do this on VMWare Player, go to the Virtual Machine’s Settings and make sure theFirst “Network Adapter” is set to Bridged
      3a. Now make sure your PC’s network connection is “live” – ie plugged into a switch or something (There are ways around this but it gets messy)
      4. GIve your PC’s network adapter an IP address that is on the same subnet as the Router interface that you are connecting to. If this is a router being set up for SDM for the first time, it will have to be in the range of

      Note: Alternative step 3 – If the VM is already running, click on the VMWare Player menu – Virtual Machine->Removable Devices->Network Adapter->Bridged

      If this doesn’t get you out of trouble, let me know.

      Chris (RedNectar)

  37. Scott Goodwin says:

    Hi Chris,

    I used a tool called winimage to convert the disk to thin, then grew it in vmware and then reallocated the partitions using the gparted live disk.

    I am struggling to get the ASA working at the moment, it keeps saying its powered up but I can console to it despite having verified working images (windows) Same with JunOS..

    I think this is an issue with Qemu, any advice welcome.



    • Kyle Shaver says:


      I am having the same issue with the ASA. Did you ever find a resolution?

  38. Scott Goodwin says:

    Hi Chris,

    First of all thanks for taking the time to produce the GNS3 vmware enviroment, Excellent work.

    I have a few questions though;

    1) Was there a specific reason why you pre-allocate the disk. Will it not function on a say a 10Gb thin disk? I only ask as I am trying to add an olive image for Junos but the disk is now full, the olive is very large.

    2) With the above in mind, I will also be unable to add my ASA + PIX, PEMU HOST.

    Thanks again for all your work, I am going to convert the disk to thin and would be happy to share.



    • rednectar says:

      Hi Scott,
      The reason for the pre-allocated disk was because I have been trying to keep this to a size that will burn to a single DVD – when I was using a “growable” disk I kept sneaking over the size for a DVD – this keeps me disciplined and under DVD size. You can convert the disk to a non-fixed size, but it takes a few commands – I don’t have time to work out the commands right now, but if you manage to work out how to do it I’d love you to tell me and I’ll add it as an article to the GNS3-Workbench page 😉

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