[Asterisk-Dev] E1, crc-4 errors

[Pauline Middelink]

On Fri, 09 May 2003 around 16:04:42 +0200, Konrad Gorski wrote:
> Hi,
> My PBX config: 
> Telco (Lucent SS7) E1 line (crc4) <=> * box + E100P, T100P, Zplex <=>
> analog phones and ATA186 (SIP and MGCP)
> * is working very good, but from Telco side are problems.
> Telco's list of errors:
> ----------------------------------------------------------
>    ERROR STATISTICS FOR : ALL MEASUREMENT TYPES
>    --------------------
>    
>    MEASUREMENT PERIOD : CURRENT DAY
>    
>    ES CALCULATION MODE          = CRC-4
>    FAC AVAILABLE TIME           = 09:58:45 HOURS
>    FAC UNAVAILABLE TIME         = 00:02:18 HOURS
>    FAC FAR-END AVAILABLE TIME   = 00:09:18 HOURS
>    FAC FAR-END UNAVAILABLE TIME = 09:51:45 HOURS
>    
>    MEASUREMENT TYPE                 ERROR     ERROR
>                                     COUNT     RATIO
>    ----------------                 -----     -----
>    
>    ERRORED SECONDS                  11     0.03062%
>    FAILED SECONDS                   138    0.38266%
>    BURSTY ERRORED SECONDS           7      0.01941%
>    SEVERELY ERRORED SECONDS         9      0.02496%
>    FRAME SLIP SECONDS               6
>    CARRIER FAILURES                 1
>    FAR-END ERRORED SECONDS          2      0.35842%
>    FAR-END FAILED SECONDS           35505 98.45271%
>    FAR-END BURSTY ERRORED SECONDS   54     0.14974%
>    FAR-END SEVERELY ERRORED SECONDS 35453 98.30852%
>    DEGRADED MINUTES                 3
> ----------------------------------------------------------
> Configuration for above test:
> Telco (Lucent SS7) E1 line (crc4) <=> E100P + wct1xxp loaded ( *
> stopped, T100P unmounted)
> zaptel.conf: 
> 	span=1,0,0,ccs,hdb3,crc4 
> 
> If E1 line configured w/o crc4 - error count is 0.
> Configuration for test w/o crc4:
> Telco (Lucent SS7) E1 line (w/o crc4) <=> E100P + wct1xxp loaded ( *
> stopped, T100P unmounted)
> zaptel.conf: 
> 	span=1,0,0,ccs,hdb3

You have to take the clock source from the Telco I think.
I.e.    span=1,1,0,ccs,hdb3

Your E1 line is now freewheeling, so sync between the telco
and your E100P shifts in and out phase.

> Buggy CRC calculation? (It's opinion of Telco's operator)
> or my E100P is faulty?

<wild guess here>
When crc4 is deactivated, the telco can't really measure
errors, or the physical connection must really be going
down. Its the crc4 checksum which gives you the possibility
to detect errors.
</wild>

    Met vriendelijke groet,
        Pauline Middelink
-- 
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For more details look at my website http://www.polyware.nl/~middelink
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