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RE: RE: RE: What is relation between clockrate and bandwidth? Common port speed 1544000, but no clock rate like posted 04/06/2002
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Since the router does not give you the speed that you want, pick the closer value
1300000 or 2000000. As it its set the DCE device, as long as the other DTE device can sync
with this, you have no problem. The clock speed give the real physical bandwidth. The bandwidth command just to let the routing protocol for metric calculation etc.

Regards
Parry

-----Original Message-----
From: thomas larus [mailto:tlarus@xxxxxxx]
Sent: Sunday, April 07, 2002 3:23 AM
To: Pablo.Narvaez@xxxxxxxxxxxxx; ccielab@xxxxxxxxxxxxxx
Subject: Re: RE: RE: What is relation between clockrate and bandwidth?
Common port speed 1544000, but no clock rate like


I know it's not a legal option.  That's my point.  That's what my screen output was there to remind us all of. My question is, what clock rate should I use for an interface that I want to be the same as a real-life T1, that is 1544000.   

I have a feeling I am worried about something that simply does not matter.  Otherwise, lots of people would have wondered about this and there would be fifty ready, right-on-point answers in five minutes, like the old "no peer neighbor-route" answer that we see every few days in answer to questions about ip ospf demand-circuit.



>>> "Narvaez, Pablo" <Pablo.Narvaez@xxxxxxxxxxxxx> 04/06/02 14:07 PM >>>
ummmm If you do a "show controll ser x" do you see that speed as a legal option? ..

R7(config-if)#clock rate 1544000
Unknown clock rate
R7(config-if)#clock rate ?      
        Speed (bits per second)
  1200
  2400
  4800
  9600
  14400
  19200
  28800
  32000
  38400
  56000
  57600
  64000
  72000
  115200
  125000
  128000
  148000
  192000
  250000
  256000
  384000
  500000
  512000
  768000
  800000
  1000000
  1300000
  2000000
  4000000
  8000000

  <300-8000000>    Choose clockrate from list above

R7(config-if)#clock rate 2000000


cheers, 

hockito






-----Original Message-----
From: thomas larus [mailto:tlarus@xxxxxxx]
Sent: Sabado, 06 de Abril de 2002 12:58 p.m.
To: Narvaez, Pablo; ccielab@xxxxxxxxxxxxxx
Subject: Re: RE: What is relation between clockrate and bandwidth?
Common port speed 1544000, but no clock rate like


I understand that the bandwidth command is for routing protocol purposes.

I am sorry that my question seeme to be about the bandwidth command.  My question is about the relations between clock rate and the real bandwidth on the interface.  I want an interface to be configured to be able to really carry 1544000 mbps.  I should think that to do this I would need to set a clock rate on the interface of a that speed or a little bit higher, but that clock rate is not an option.  
  You said: 
" For the lab, you may configure the clockrate as you wish as long as both ends match. Just keep in mind that the bw will be responsable for the routing protocol decisions ..."

I just tried to set the clockrate to 1544000, and it would not let me.  (We have all tried to do this at some point, probably.)



r2613(config-if)#clock rate ?
        Speed (bits per second)
  1200
  2400
  4800
  9600
  14400
  19200
  28800
  32000
  38400
  56000
  57600
  64000
  72000
  115200
  125000
  128000
  148000
  192000
  250000
  256000
  384000
  500000
  512000
  768000
  800000
  1000000
  1300000
  2000000
  4000000
  8000000

  <300-4000000>    Choose clockrate from list above

r2613(config-if)#clock rate 1544000
Unknown clock rate


  So which clock rate setting should I use in a home lab scenario setting where I am trying to emulate a DS-1 of 1544000. Should I use clock rate of 2000000?  What do other folks use?  This must be a question lots of you have had, and found an adequate, and perhaps obvious answer.

Thanks for the excellent point about frame relay multipoint.

Thanks in advance.

Tom Larus 


>>> "Naraez, Pablo" <Pablo.Narvaez@xxxxxxxxxxxxx> 04/06/02 13:29 PM >>>
The bandwith command if for routing protocols only, not for layer1 bandwith/speed nor to indicate the rate of the line clock. You may have a clock rate of 64000 and bandwith of 128k; most of the time you may want to set both at the same rate in order for the routing protocol to work properly and calculate a "real" metric for that link,

Some other times you may need to change that bw value, like in  multipoint sub-if with EIGRP not to overflow the low speed PVCs whereas you have to keep the clockrate according to the provided clock. In a real scenario, most of the times you don't have to deal with clockrates in the interfaces (usually DTEs for endpoints) since you take the clock from internal line and leave that job to the csu/dsu.

For the lab, you may configure the clockrate as you wish as long as both ends match. Just keep in mind that the bw will be responsable for the routing protocol decisions ...

cheers,

hockito


-----Original Message-----
From: thomas larus [mailto:tlarus@xxxxxxx]
Sent: Sabado, 06 de Abril de 2002 12:02 p.m.
To: ccielab@xxxxxxxxxxxxxx
Subject: What is relation between clockrate and bandwidth? Common port
speed 1544000, but no clock rate like


On my routers, I do not have the option of choosing a clock rate anywhere near 1544000 (the closest rate is 1300000), yet in countless scenarios (like Solie's) we set the frame relay cir to 1544000.  How can we have a port speed of 1544000 when that is never an option on our routers as a clockspeed.

Could someone explain this.
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