Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Finding the RX clock on a Serial interface

Hi - this has been a mistery to me for a looong time.

Is there any way of doing a show command that will show what clock rate a Serial interface is running (PPP/HDLC/FR)

I have looked at show controllers s0 ..and show int s0


Re: Finding the RX clock on a Serial interface

PPP/HDLC/FR are the encaps on a serial connection. If you are looking for this, this will show up in the running config under the controller or interface config (depending on the module you are using). The defaults will not be listed. For example, if you are using encap HDLC (cisco default), it will not show up in the running config even if you type it in.

Hope this helps.

New Member

Re: Finding the RX clock on a Serial interface


Okay..let's explain a little better..

Normally if you connect a Cisco router to a DCE like a modem etc. The clock is received from the DCE - right ? We usually use X.21 or V.35

is there any way of displaying the clock rate received from the DCE ?

Well, to list the encaps is irrelevant - as they are layer2 ..and have nothing to to with the physical interface. - sorry about that.

- benni


Re: Finding the RX clock on a Serial interface

benni show controllers does show you the clock rate - i guess it depends on what ios version you aer using. If you are using an old variant then the only way to find the clock is by picking up the phone and asking your SP/Telco.

New Member

Re: Finding the RX clock on a Serial interface

well.. here is a sh controllers from a Cisco 2811 running c2800nm-advipservicesk9-mz.123-11.T6.bin

I looked at 2620 with 12.2 now 2811 with 12.3T ...etc. and I can't figure this out.

But - this is not a operational issue .. I just like to know if this is possible.

(somethimes we have performance problems with telco - and it would be nice to see how they configure the interface)

Nis310-rtr1#show controllers serial 0/2/0

Interface Serial0/2/0

Hardware is GT96K

DTE V.11 (X.21)idb at 0x4561A734, driver data structure at 0x45622548

wic_info 0x45622B3C

Physical Port 5, SCC Num 5

MPSC Registers:

MMCR_L=0x000304C0, MMCR_H=0x00000000, MPCR=0x00000100

CHR1=0x00FE007E, CHR2=0x00000000, CHR3=0x00000648, CHR4=0x00000000

CHR5=0x00000000, CHR6=0x00000000, CHR7=0x00000000, CHR8=0x00000000

CHR9=0x00000000, CHR10=0x00003000

SDMA Registers:

SDC=0x00002201, SDCM=0x00000080

CRDP=0x0F640D90, CTDP=0x0F68B5D0, FTDB=0x0F68B5D0

Main Routing Register=0x77077700 BRG Conf Register=0x00480000

Rx Clk Routing Register=0x00800088 Tx Clk Routing Register=0x00900010

GPP Registers:

Conf=0x50055600, Io=0x50055600, Data=0xFFFFFBFF, Level=0x00001800

TDM FPGA Registers:

vmcr[0] = 0x0043C0C0, vmcr[1] = 0x00000000,

vmcr[2] = 0x00010040, vmcr[3] = 0x00000000

ntrcr0 = 0x00000000, ntrcr1 = 0x00000000

tdmcr = 0x0000006A, labcr = 0x00000000, tpllr_cr = 0x00000000

nhr = 0x66606673, isr = 0x00000B00, imr = 0x00000000

3719 input aborts on receiving flag sequence

0 throttles, 0 enables

3304 overruns

0 transmitter underruns

0 transmitter CTS losts

84655037 rxintr, 82998879 txintr, 0 rxerr, 0 txerr

151230824 mpsc_rx, 0 mpsc_rxerr, 57 mpsc_rlsc, 575 mpsc_rhnt, 151230678 mpsc_rfsc

18 mpsc_rcsc, 0 mpsc_rovr, 0 mpsc_rcdl, 0 mpsc_rckg, 0 mpsc_bper

0 mpsc_txerr, 76846460 mpsc_teidl, 0 mpsc_tudr, 0 mpsc_tctsl, 0 mpsc_tckg

0 sdma_rx_sf, 0 sdma_rx_mfl, 3304 sdma_rx_or, 3719 sdma_rx_abr, 5824 sdma_rx_no

0 sdma_rx_de, 0 sdma_rx_cdl, 7574 sdma_rx_ce, 0 sdma_tx_rl, 0 sdma_tx_ur, 0 sdma_tx_ctsl

0 sdma_rx_reserr, 0 sdma_tx_reserr

0 rx_bogus_pkts, rx_bogus_flag FALSE

0 sdma_tx_ur_processed


Re: Finding the RX clock on a Serial interface

here is an output of a show controllers for me.

cable type : V.24 (RS-232) DTE cable, received clockrate 9600 <--------- its ok for me so it must be interface specific

base0 registers=0x3D800000, base1 registers=0x3D802000

mxt_ds=0x62CB9070, rx ring entries=37, tx ring entries=64

rxring=0x2000F8C0, rxr shadow=0x6295CEFC, rx_head=25

txring=0x2000FA20, txr shadow=0x6295D0F0, tx_head=7, tx_tail=7,

throttled=0, enabled=0

halted=0, last halt reason=0

Microcode fatal errors=0

rx_no_eop_err=0, rx_no_stp_err=0, rx_no_eop_stp_err=0

rx_no_buf=0, rx_soft_overrun_err=0, dump_err= 0, bogus=0, mxt_f

tx_underrun_err=0, tx_soft_underrun_err=0, tx_limited=1(2)

tx_fullring=0, tx_started=92487 mxt_flush_count=0

rx_int_count=92487, tx_int_count=92488

Half-duplex hdx=0x6295CC48, summary:-