From: Jason Gardiner (gardiner@xxxxxxxxxx)
Date: Fri May 18 2001 - 19:25:24 GMT-3
Jeongwoo:
There should only be one timing source for a circuit. In most instances
this is provided by the DACS, if it is used. If there are multiple
clocks on a circuit, say each CSU is set to internal, then the framing
gets out of sync as each side expects that it is providing the timing
for the circuit.
Clocks are defined by stratum, which is essentially a spec for the
minimum length of time allowed by the source before a timing slip
occurs. Routers and CSUs are generally stratum 3, which has a minimum
slip time of 6 minutes. Some may go much longer, but these are not
reliable clocks. DACS generally tie into atomic clocks that are stratum
1, which has a minimum slip time of about 72 days. SONET/SDH equipment
needs to use stratum 1 due to the tighter error tolerance needed by the
higher line speeds.
********* SLIGHTLY OFF TOPIC *************
If anyone wants, I've a Powerpoint Presentation that I created for a
training class. It has some troubleshooting and other information that
some of you may find useful. It's about 4.5 MB, but if you're
interested, drop me a line and I'll e-mail it to you.
Jeongwoo Park wrote:
>
> Hey jason
> Thanks for your input.
> Why should it be set to network or line rather than internal? is it line or
> DTE by the way?
> the csu that I have has three option for clock source: line, dte, and
> internal.
> Can you tell me the brief difference of those?
>
> Thanks
>
> jp
> -----Original Message-----
> From: gardiner@sprint.net [mailto:gardiner@sprint.net]
> Sent: Friday, May 18, 2001 8:31 AM
> To: Jeongwoo Park
> Subject: Re: point to point T1 troubleshooting.
>
> Hello,
>
> First of all, the Bandwidth on the interface is E-1 rather than T-1, but
> that is merely cosmetic. The errors that are appearing might be related
> to timing, but I've never seen giants on a serial line.
>
> Check the timing on the CSU/DSUs on both ends. They should be set to
> network or line rather than internal. But I think that telco lied to
> you.
>
> Jeongwoo Park wrote:
> >
> > Hi all
> > Have anyone troubleshootted T1?
> > it is ppp encapsulation, leased line.
> > LEC(local exchange carrier) said circuit is fine, which I doubt.
> > Router config is fine, I believe.
> > here is output of "sh int s2/0"
> >
> > #sh int s2/0
> > Serial2/0 is up, line protocol is down
> > Hardware is M4T
> > Description: Leased Line to branch
> > Internet address is 10.10.14.86/30
> > MTU 1500 bytes, BW 2048 Kbit, DLY 20000 usec,
> > reliability 255/255, txload 1/255, rxload 1/255
> > Encapsulation PPP, crc 16, loopback not set
> > Keepalive set (10 sec)
> > LCP Listen
> > Closed: IPCP, CDPCP
> > Last input never, output 00:00:03, output hang never
> > Last clearing of "show interface" counters 18:08:32
> > Input queue: 0/75/0 (size/max/drops); Total output
> > drops: 0
> > Queueing strategy: weighted fair
> > Output queue: 0/1000/64/0 (size/max
> > total/threshold/drops)
> > Conversations 0/1/256 (active/max active/max
> > total)
> > Reserved Conversations 0/0 (allocated/max
> > allocated)
> > 5 minute input rate 0 bits/sec, 0 packets/sec
> > 5 minute output rate 0 bits/sec, 0 packets/sec
> > 0 packets input, 0 bytes, 0 no buffer
> > Received 0 broadcasts, 0 runts, 2368 giants, 0
> > throttles
> > 8940 input errors, 1913 CRC, 0 frame, 6028
> > overrun, 0 ignored, 999 abort
> > 13556 packets output, 189784 bytes, 0 underruns
> > 0 output errors, 0 collisions, 3438 interface
> > resets
> > 0 output buffer failures, 0 output buffers
> > swapped out
> > 3672 carrier transitions DCD=up DSR=up
> > DTR=up RTS=up CTS=up
> > **Please read:http://www.groupstudy.com/list/posting.html
> --
> Thanks,
>
> Jason Gardiner
> Engineering Services
> Sprint E|Solutions
>
> "The only thing to prevent what's past is to put a stop to it before it
> happens."
> - Sir Boyle Roche
-- Thanks,Jason Gardiner Engineering Services Sprint E|Solutions
"The only thing to prevent what's past is to put a stop to it before it happens." - Sir Boyle Roche **Please read:http://www.groupstudy.com/list/posting.html
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