Which OS is behind IOS ?

Discussion in 'Cisco' started by Georg Dingler, Sep 26, 2006.

  1. Hello,

    is IOS a custom OS or is it based on VXWorks or an other embedded System
    like that ?

    --
    Georg
    www.dingler-it.de
     
    Georg Dingler, Sep 26, 2006
    #1
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  2. Georg Dingler wrote:
    > Hello,
    >
    > is IOS a custom OS or is it based on VXWorks or an other embedded System
    > like that ?
    >


    For the "standard" IOS, it is an OS fully designed by Cisco.
    For IOS-XR / Modular IOS (ION), it is based on QNX.
     
    Christophe Fillot, Sep 26, 2006
    #2
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  3. Hi Georg,

    Cisco IOS has a "monolithic" architecture, which means that it runs as
    a single image and all processes share the same memory space.

    There is no memory protection between processes, which means that bugs
    in IOS code can potentially corrupt data used by other processes.

    It also has a "run to completion" scheduler, which means that the
    kernel does not pre-empt a running process -- the process must make a
    kernel call before other processes get a chance to run.

    For Cisco products that required very high availability, such as the
    Cisco CRS-1, these limitations were not acceptable.

    In addition, competitive router operating systems that emerged 10-20
    years after IOS, such as Juniper's JunOS, were designed not to have
    these limitations.

    Cisco's response was to develop a new version of Cisco IOS called
    IOS-XR that offered modularity and memory protection between processes,
    lightweight threads, pre-emptive scheduling and the ability to
    independently re-start failed processes.

    IOS-XR uses a 3rd party real-time operating system microkernel (QNX),
    and a large part of the current IOS code was re-written to take
    advantage of the features offered by the new kernel -- a massive
    undertaking.

    But the microkernel architecture removes from the kernel all process
    that are not absolutely required to run in the kernel, and executes
    them as processes similar to the application processes.

    Through this method, IOS-XR is able to achieve the high availability
    desired for the new router platform.

    Thus IOS and IOS-XR are very different codebases, though related in
    functionality and design.

    In 2005, Cisco introduced IOS-XR on the Cisco 12000 series platform,
    extending the microkernel architecture from the CRS-1 to Cisco's widely
    deployed core router.

    Recently (in 2006), Cisco has made available IOS Software Modularity
    which extends the QNX microkernel into a more traditional IOS
    environment, but still providing the software upgrade capabilities that
    customers are demanding.

    It is currently available on the Catalyst 6500 enterprise switch.

    Sincerely,

    Brad Reese
    BradReese.Com - Cisco Repair
    http://www.bradreese.com/cisco-big-iron-repair.htm
    1293 Hendersonville Road, Suite 17
    Asheville, North Carolina USA 28803
    USA & Canada: 877-549-2680
    International: 828-277-7272
    Fax: 775-254-3558
    AIM: R2MGrant
    BradReese.Com - Cisco Power Supply Headquarters
    http://www.bradreese.com/cisco-power-supply-inventory.htm
     
    www.BradReese.Com, Sep 26, 2006
    #3
  4. Thank you very much for this information !

    PS: Will IOS-XR be available for the smaller Routers or will it only be
    available on the high end models ?

    Georg

    www.BradReese.Com schrieb:
    > Hi Georg,
    >
    > Cisco IOS has a "monolithic" architecture, which means that it runs as
    > a single image and all processes share the same memory space.
    >
    > There is no memory protection between processes, which means that bugs
    > in IOS code can potentially corrupt data used by other processes.
    >
    > It also has a "run to completion" scheduler, which means that the
    > kernel does not pre-empt a running process -- the process must make a
    > kernel call before other processes get a chance to run.
    >
    > For Cisco products that required very high availability, such as the
    > Cisco CRS-1, these limitations were not acceptable.
    >
    > In addition, competitive router operating systems that emerged 10-20
    > years after IOS, such as Juniper's JunOS, were designed not to have
    > these limitations.
    >
    > Cisco's response was to develop a new version of Cisco IOS called
    > IOS-XR that offered modularity and memory protection between processes,
    > lightweight threads, pre-emptive scheduling and the ability to
    > independently re-start failed processes.
    >
    > IOS-XR uses a 3rd party real-time operating system microkernel (QNX),
    > and a large part of the current IOS code was re-written to take
    > advantage of the features offered by the new kernel -- a massive
    > undertaking.
    >
    > But the microkernel architecture removes from the kernel all process
    > that are not absolutely required to run in the kernel, and executes
    > them as processes similar to the application processes.
    >
    > Through this method, IOS-XR is able to achieve the high availability
    > desired for the new router platform.
    >
    > Thus IOS and IOS-XR are very different codebases, though related in
    > functionality and design.
    >
    > In 2005, Cisco introduced IOS-XR on the Cisco 12000 series platform,
    > extending the microkernel architecture from the CRS-1 to Cisco's widely
    > deployed core router.
    >
    > Recently (in 2006), Cisco has made available IOS Software Modularity
    > which extends the QNX microkernel into a more traditional IOS
    > environment, but still providing the software upgrade capabilities that
    > customers are demanding.
    >
    > It is currently available on the Catalyst 6500 enterprise switch.
    >
    > Sincerely,
    >
    > Brad Reese
    > BradReese.Com - Cisco Repair
    > http://www.bradreese.com/cisco-big-iron-repair.htm
    > 1293 Hendersonville Road, Suite 17
    > Asheville, North Carolina USA 28803
    > USA & Canada: 877-549-2680
    > International: 828-277-7272
    > Fax: 775-254-3558
    > AIM: R2MGrant
    > BradReese.Com - Cisco Power Supply Headquarters
    > http://www.bradreese.com/cisco-power-supply-inventory.htm
    >



    --
    Georg
    www.dingler-it.de
     
    Georg Dingler, Sep 26, 2006
    #4
  5. Hi Georg,

    To further answer your questions, please contact directly:

    Mr. Harold Ritter, CCIE No. 4168.

    Harold is a network consulting engineer for Cisco Advanced Network
    Services.

    He is responsible for helping Cisco top-tier customers to design,
    implement, and troubleshoot routing protocols in their environment.

    He has been working as a network engineer for more than eight years.

    Harold's email address:

    hritter *at* cisco.com

    Georg, hope this helps.

    Brad Reese
    Cisco Network Engineer Directory
    http://www.bradreese.com/network-engineer-directory.htm
     
    www.BradReese.Com, Sep 26, 2006
    #5
  6. Georg Dingler

    roger t Guest

    When I use cisco IOS all I see is unix customized by cisco
     
    roger t, Sep 27, 2006
    #6
  7. In article <>,
    "roger t" <> wrote:

    > When I use cisco IOS all I see is unix customized by cisco


    There's nothing Unix-related in IOS. The original designers came from
    DEC, I believe, and patterned its CLI somewhat after TENEX and TOPS-20.
    If you're talking about the automatic completion, that's something Unix
    adopted from DEC (it first appeared in tcsh, and the "t" is often
    considered to stand for TENEX).

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***
     
    Barry Margolin, Sep 27, 2006
    #7
  8. Georg Dingler

    Neil Cherry Guest

    Neil Cherry, Sep 27, 2006
    #8
  9. Georg Dingler

    Sam Wilson Guest

    In article <>,
    Barry Margolin <> wrote:

    > In article <>,
    > "roger t" <> wrote:
    >
    > > When I use cisco IOS all I see is unix customized by cisco

    >
    > There's nothing Unix-related in IOS. The original designers came from
    > DEC, I believe, and patterned its CLI somewhat after TENEX and TOPS-20.
    > If you're talking about the automatic completion, that's something Unix
    > adopted from DEC (it first appeared in tcsh, and the "t" is often
    > considered to stand for TENEX).


    <nitpick>
    I believe, from messages from within Cisco on the old
    mailing list, that what was implemented was
    taken from the Korn shell (ksh) rather than tcsh.
    </nitpick>

    Sam
     
    Sam Wilson, Sep 27, 2006
    #9
  10. Georg Dingler

    Neil Cherry Guest

    On Wed, 27 Sep 2006 10:48:33 +0100, Sam Wilson wrote:
    > In article <>,
    > Barry Margolin <> wrote:
    >
    >> In article <>,
    >> "roger t" <> wrote:
    >>
    >> > When I use cisco IOS all I see is unix customized by cisco

    >>
    >> There's nothing Unix-related in IOS. The original designers came from
    >> DEC, I believe, and patterned its CLI somewhat after TENEX and TOPS-20.
    >> If you're talking about the automatic completion, that's something Unix
    >> adopted from DEC (it first appeared in tcsh, and the "t" is often
    >> considered to stand for TENEX).

    >
    ><nitpick>
    > I believe, from messages from within Cisco on the old
    > mailing list, that what was implemented was
    > taken from the Korn shell (ksh) rather than tcsh.
    ></nitpick>


    Oh, good point! 'We' (lots of folks) used to bug Cisco to get the
    command line editing put in the routers. I prefered to ask Cisco when
    they were going to add emacs (the full X version :).

    --
    Linux Home Automation Neil Cherry
    http://www.linuxha.com/ Main site
    http://linuxha.blogspot.com/ My HA Blog
    http://home.comcast.net/~ncherry/ Backup site
     
    Neil Cherry, Sep 27, 2006
    #10
  11. In article <>,
    Sam Wilson <> wrote:

    > In article <>,
    > Barry Margolin <> wrote:
    >
    > > In article <>,
    > > "roger t" <> wrote:
    > >
    > > > When I use cisco IOS all I see is unix customized by cisco

    > >
    > > There's nothing Unix-related in IOS. The original designers came from
    > > DEC, I believe, and patterned its CLI somewhat after TENEX and TOPS-20.
    > > If you're talking about the automatic completion, that's something Unix
    > > adopted from DEC (it first appeared in tcsh, and the "t" is often
    > > considered to stand for TENEX).

    >
    > <nitpick>
    > I believe, from messages from within Cisco on the old
    > mailing list, that what was implemented was
    > taken from the Korn shell (ksh) rather than tcsh.
    > </nitpick>


    Since I didn't say that it was taken from tcsh, your "rather than"
    doesn't really make sense. I said that Cisco got it from DEC (maybe it
    was VMS rather than TENEX/TOPS-20), not from any Unix source.

    The most obvious way that IOS differs from Unix is the lack of "-" to
    introduce command options. On the other hand, there are a few commands
    that use /option:value, a very VMS-ish thing.

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***
     
    Barry Margolin, Sep 27, 2006
    #11
  12. Georg Dingler

    Pirke Guest

    Some UNIX based Cisco appliances like the WLSE have a IOS-like interface.
    Maybe that is what "roger t" means ...

    "Neil Cherry" <> wrote in message
    news:...
    > On 26 Sep 2006 20:00:49 -0700, roger t wrote:
    >> When I use cisco IOS all I see is unix customized by cisco

    >
    > When I use Cisco IOS all I see is VMS. :) Don't worry I know
    > Cisco isn't VMS. I really don't know how you get Unix though.
    > (???).
    >
    >
    > --
    > Linux Home Automation Neil Cherry
    > http://www.linuxha.com/ Main site
    > http://linuxha.blogspot.com/ My HA Blog
    > http://home.comcast.net/~ncherry/ Backup site
     
    Pirke, Sep 28, 2006
    #12
  13. Georg Dingler

    Sam Wilson Guest

    In article <>,
    Barry Margolin <> wrote:

    > In article <>,
    > Sam Wilson <> wrote:
    >
    > > In article <>,
    > > Barry Margolin <> wrote:
    > >
    > > > In article <>,
    > > > "roger t" <> wrote:
    > > >
    > > > > When I use cisco IOS all I see is unix customized by cisco
    > > >
    > > > There's nothing Unix-related in IOS. The original designers came from
    > > > DEC, I believe, and patterned its CLI somewhat after TENEX and TOPS-20.
    > > > If you're talking about the automatic completion, that's something Unix
    > > > adopted from DEC (it first appeared in tcsh, and the "t" is often
    > > > considered to stand for TENEX).

    > >
    > > <nitpick>
    > > I believe, from messages from within Cisco on the old
    > > mailing list, that what was implemented was
    > > taken from the Korn shell (ksh) rather than tcsh.
    > > </nitpick>

    >
    > Since I didn't say that it was taken from tcsh, your "rather than"
    > doesn't really make sense. I said that Cisco got it from DEC (maybe it
    > was VMS rather than TENEX/TOPS-20), not from any Unix source.


    :) How nitpicky do you want to get? I concede that you didn't say
    Cisco got the command completion from Unix, however since it did come
    from ksh then in fact they DID get it from Unix. If you really want to
    get picky then your parenthetical comment about it first appearing in
    tcsh is only true for Unix since it had previously appeared in TENEX.

    > The most obvious way that IOS differs from Unix is the lack of "-" to
    > introduce command options. On the other hand, there are a few commands
    > that use /option:value, a very VMS-ish thing.


    A very DEC thing in general - I was a relatively late user of DEC OSs -
    TOPS-10 and various stuff on PDP-8s in the late 1970s, and RT-11 in the
    early 80s, by which time CP/M had also borrowed the command names and
    syntax.


    Sam
     
    Sam Wilson, Sep 28, 2006
    #13
  14. Georg Dingler

    sphealey Guest

    Every history I have ever read of Cisco says that the two original
    founders were long-time Stanford DECSystem-10/DECSystem-20 hackers (and
    perhaps PDP-6 as well), which would make sense since Stanford in that
    era was a fanatical bastion of 36-bit Digital systems. After cashing
    out one of the Cisco founders want on to fund XKL which for a while was
    building new DEC-10 compatibles running a clone of TOPS-10.

    TOPS-10 hackers in particular found Unix(tm) sort of amusing in a
    pat-the-little-brother-on-the-head way, and I doubt that when starting
    out to create a new CLI that any Unix variant would have been the basis
    of choice.

    sPh
     
    sphealey, Sep 28, 2006
    #14
  15. Georg Dingler

    roger t Guest

    Pirke wrote:
    > Some UNIX based Cisco appliances like the WLSE have a IOS-like interface.
    > Maybe that is what "roger t" means ...
    >


    >From a useability standpoint it all looks like *nix to me. Being that I

    was born in 1984,
    I had no idea what DEC was. Thanks to the users who pointed DEC out and
    for
    the history lesson.
    http://www.networkworld.com/supp/2006/anniversary/032706-routerman.html

    this article confirms what you guys are saying.
    Roger Thompson
     
    roger t, Sep 29, 2006
    #15
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