Re: Clock Rate

Now I see what u r trying to say ( if i am not wrong )

Whatever statement I made above was applicable to the end that connect the 2
ends of cables ( not the end that goes into serial port of WIC / HWIC card )

Hence I said that there is a male and a female part (which is true ! ) and
therefore I mentioned the official names of the cables as well .

Gaurav Madan

On Mon, Jul 18, 2011 at 10:21 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> 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<gauravmadan1177_at_gmail.com>
>> >
>> <mailto:gauravmadan1177_at_gmail.
>>
>> <mailto:gauravmadan1177_at_gmail.**>__**com
>> <gauravmadan1177_at_gmail.com
>> <mailto:gauravmadan1177_at_gmail.**com<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
>>
>>
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>>
>>
>>
>>
>> -- 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
>>
>>
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>>
>> -- 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

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Received on Mon Jul 18 2011 - 22:38:31 ART