Re: Clock Rate

GAURAV MADAN @ 18/07/2011 13:44 -0300 dixit:
> I DONT agree to you last point .
>
> U have male and female parts in smart serial cables .

Let's recap: all cables have 2 connectors, right ?
The smart serial cables have one smart serial connector and one
that is dependent on the type of cable.

> Just take following example :
>
> CAB-SS-V35MT and CAB-SS-V35FC

CAB-SS-V35MT is a SS to V.35 male, so it has two males.
CAB-SS-V35FS is a SS to V.35 female, so one of each.

Those are two cables!
What is that you don't agree with ?

-Carlos

>
> The ends that goes in WIC / HWIC card is the same ..(atleast physically
> they look the same)
> But the other end of cable definatly is a male/female .
>
> HTH
> Gaurav Madan
>
>
>
> On Mon, Jul 18, 2011 at 9:42 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar
> <mailto:tron_at_huapi.ba.ar>> wrote:
>
> GAURAV MADAN @ 18/07/2011 11:52 -0300 dixit:
>
> Agreed ..
> wahtever you told is correct ! thats what a clocking and a DCE
> end means .
>
> Whatever I told was from Cisco point of view and how things work
> in cisco
> routers environment . Hence what i meant was that cisco routers
> only act as
> DCE .(providing clock)
>
>
> I don't think this is right. Routers (including cisco's) are DTEs.
> Their ability to provide clock do not make them DCEs, even if we
> call them so. But this is semantic.
>
>
> As far as your last point is concerned ; Cisco does sell the
> cables with one
> end as DCE and other end as DTE . In fact all the SS (smart
> serial) cables
> have a Male part and a female part (connector in middle) and
> hence have a
> DCE end and a DTE end .
>
>
> This is confusing. There's only one gender for SS cables, and I
> would say they are "male". If that is the case, a DTE cable has two
> males,
> and a DCE cable has one of each. Note that a "DTE" cable is one that
> signals the router to behave as a DTE.
>
> The cables I was referring to have two SS connectors.
>
> -Carlos
>
>
>
>
> Thnx
> Gaurav Madan
> CCIE
>
> On Mon, Jul 18, 2011 at 3:35 PM, Carlos G Mendioroz
> <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>>wrote:
>
> Gaurav,
> I would like to share my understanding of what clock is.
> I guess it should be clear that clock rate is of no use in
> dynamips and its clients (dynagen/GNS3), as no phy layer
> emulation takes place there, and data is transferred using
> UDP between interfaces.
>
> When you have an asynchronous link, the bits timing is
> recognized
> on each byte boundary in an independent way. Each byte is
> independent of
> the previous, and there is no out of band reference between
> Tx and Rx.
> This is expensive in terms of time, because you need start
> bits and
> stop bits.
>
> So in synchronous links, a reference timing is kept at the
> endpoints
> to be reused for all bits/bytes. DCE's do that (recover the
> clock)
> and share it via an out of band signal with the DTE. Each
> side of
> a serial link is supposed to have a DCE and a DTE.
>
> So routers (DTEs) should actually use clock info from its
> associated DCE.
> Routers has no business in clocking.
>
> But we sometimes use routers connected back to back, and we
> don't want
> to set up DCEs, so we use sort of null modems, thanks to the
> ability
> of routers to fake being a DCE to the linked router. This
> faking implies
> the provision of a clock reference, hence the clock rate
> command, and
> a specially wired cable that connects a clock source pin on
> the smart
> connector to the pin used by DCEs to provide the clock. What
> we call
> a DCE cable. Routers recognize the presence of such cable
> (that's why
> we call them smart cables I guess :) and enable the clocking.
>
> Last, some actually use cables that combine a DTE cable and
> a DCE
> cable, becoming real "null modems". Those cables do have a
> DCE end
> and a DTE end indeed. AFAIK, cisco does not sell such
> cables, but
> they are handly in labs.
>
> HTH,
> -Carlos
>
>
> GAURAV MADAN @ 17/07/2011 11:35 -0300 dixit:
>
> :)))))
>
> DTE , DCE are devices (routers in your case) each having
> defined purpose .
>
> But you need to plug in right cable to right device .
> Physically a serial WIC / HWIC card plugged in a router
> can assume a role
> of a DTE as well as DCE.
> It depends on the cable that is connected to serial
> interface that the end
> takes a role of DCE or a DTE .
>
> Each serial cable type (RS 232 , V.35 , 449 , 530 etc
> etc) have a DTE end
> and a DCE end ; so depending on what is plugged in where
> .. the end is
> defined .
>
> Hope some clarity this time ,
>
> Gaurav Madan
> CCIE .
>
> On Sun, Jul 17, 2011 at 7:05 PM, Carlos G Mendioroz
> <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar><mailto:
> tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>>> wrote:
>
> This is getting so distant from reality ... as a lab
> can get.
> What exactly is DCE and DTE ? Is a router a DTE or a DCE ?
> Is the cable a DCE or a DTE ? :)
> -Carlos
>
> Radioactive Frog @ 17/07/2011 01:57 -0300 dixit:
>
> Great explaination Gaurav.
> Just would add on top of gaurav's statement - You
> need a very
> SPECIFIC
> cables that has one end DTE and other end DCE to
> get it working.
>
> On Sun, Jul 17, 2011 at 2:12 AM, GAURAV MADAN
> <gauravmadan1177_at_gmail.com
> <mailto:gauravmadan1177_at_gmail.com>
> <mailto:gauravmadan1177_at_gmail.
> <mailto:gauravmadan1177_at_gmail.>__**com
> <gauravmadan1177_at_gmail.com
> <mailto:gauravmadan1177_at_gmail.com>>
>
> __wrote:
>
>
> Things to consider here are :
>
> 1) Clock rate is applicable to DCE devices and
> not on DTE
> devices
> 2) Devices can be categorized as DCE or DTE
> depending the
> cable connected
> to
> serial interface.
> 3) Generally DCE devices are FR switch etc.
> 4) If you are configuring the back to back
> connection ;
> configure "clock
> rate <> " CLI on DCE end only
> 5) I think latest IOS on serial HWIC will take
> clock rate
> command only on
> DCE end and not on DTE end . However older IOS
> used to take
> it on any
> device
> 6) Any rate is good ... as long as it is
> working .. default
> 9600 bps should
> be OK .
>
>
> HTH
> Gaurav Madan
> CCIE
>
> On Sat, Jul 16, 2011 at 9:36 PM,
> <jhnrose401_at_gmail.com <mailto:jhnrose401_at_gmail.com>
> <mailto:jhnrose401_at_gmail.com
> <mailto:jhnrose401_at_gmail.com>>> wrote:
>
> Dear
>
> I want to know what clock rate i will use
> when i am in
> the lab or when i
>
> am
>
> using
> dynamips what is the method or way i will
> configure
> the correct clock
> rate to
> my routers
>
> Eg
>
> For DCE i ll configure the clock rate not
> for DTE correct
>
> if both devices are DCE i will define CR
> on both or in a
> single devices.
>
> R1 --ser1/0 -------------------s1/0 R2
>
> I am facing problem my ospf adj flap after
> few minutes
> is CR are the
>
> reason
>
> R1 = s1/0 ip add 10.1.1.1/24
> <http://10.1.1.1/24> <http://10.1.1.1/24> and
> loop back 1.1.1.1/24 <http://1.1.1.1/24>
> <http://1.1.1.1/24>
> R2 = s1/0 ip add 10.1.1.2/24
> <http://10.1.1.2/24> <http://10.1.1.2/24> and
> loop back 2.1.1.1/24 <http://2.1.1.1/24>
> <http://2.1.1.1/24>
>
> clock rate 64000 on both sides
> R1 and R2
>
> router ospf 1
> net 0.0.0.0 255.255.255.255 are 0
>
> thks
>
>
> Blogs and organic groups at
> http://www.ccie.net
>
> ________________________________**
> ________________________________**_______________
> Subscription information may be found at:
>
> http://www.groupstudy.com/__**__list/CCIELab.html
> <http://www.groupstudy.com/__**list/CCIELab.html><http://www.__groupstudy.com/__list/CCIELab.__html
> <http://www.groupstudy.com/__list/CCIELab.html>>
>
> <http://www.groupstudy.com/**__list/CCIELab.html
> <http://www.groupstudy.com/**list/CCIELab.html><http://www.__groupstudy.com/list/CCIELab.__html
> <http://www.groupstudy.com/list/CCIELab.html>>
>
> Blogs and organic groups at http://www.ccie.net
>
>
> ________________________________**________________________________
> **_______________
> Subscription information may be found at:
>
> http://www.groupstudy.com/__**__list/CCIELab.html
> <http://www.groupstudy.com/__**list/CCIELab.html><http://www.__groupstudy.com/__list/CCIELab.__html
> <http://www.groupstudy.com/__list/CCIELab.html>>
>
> <http://www.groupstudy.com/**__list/CCIELab.html
> <http://www.groupstudy.com/**list/CCIELab.html><http://www.__groupstudy.com/list/CCIELab.__html
> <http://www.groupstudy.com/list/CCIELab.html>>
>
>
> Blogs and organic groups at http://www.ccie.net
>
>
> ________________________________**________________________________**
> _______________
> Subscription information may be found at:
> http://www.groupstudy.com/__**__list/CCIELab.html
> <http://www.groupstudy.com/__**list/CCIELab.html><http://www.__groupstudy.com/__list/CCIELab.__html
> <http://www.groupstudy.com/__list/CCIELab.html>>
> <http://www.groupstudy.com/**__list/CCIELab.html
> <http://www.groupstudy.com/**list/CCIELab.html><http://www.__groupstudy.com/list/CCIELab.__html
> <http://www.groupstudy.com/list/CCIELab.html>>
>
>
>
>
>
>
>
> -- Carlos G Mendioroz <tron_at_huapi.ba.ar
> <mailto:tron_at_huapi.ba.ar> <mailto:tron_at_huapi.ba.ar
> <mailto:tron_at_huapi.ba.ar>
> LW7 EQI Argentina
>
>
>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar
> <mailto:tron_at_huapi.ba.ar>> LW7 EQI Argentina
>
>
>
> Blogs and organic groups at http://www.ccie.net
>
> ___________________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/__list/CCIELab.html
> <http://www.groupstudy.com/list/CCIELab.html>
>
>
>
>
>
>
>
>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>>
> LW7 EQI Argentina
>
>

-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net