SNR / SNMP Calculs

osgpcqosg · ‎03-28-2011

We are looking to make some graph about the SNR values of the 8xx we have in customers ofice.

For the 878 router we have some problems to understand how the SNR calcul is done.

878shdsl#sh controllers dsl 0

Loop Attenuation: 9.0 dB

Transmit Power: 13.5 dB
Receiver Gain: 24.420 dB
SNR Sampling: 39.5920 dB

vincent@sistemes-vincent:~$ snmpwalk -c public -v 1 x.x.x.x .1.3.6.1.2.1.10.48.1.5.1.1
SNMPv2-SMI::transmission.48.1.5.1.1.10.1.2.1 = INTEGER: 0
SNMPv2-SMI::transmission.48.1.5.1.1.10.2.1.1 = INTEGER: 9

incent@sistemes-vincent:~$ snmpwalk -c public -v 1 x.x.x.x .1.3.6.1.2.1.10.48.1.5.1.2.10.2.1.1
SNMPv2-SMI::transmission.48.1.5.1.2.10.2.1.1 = INTEGER: 17

This is the result of this calcul: 10 log (9÷13.5) = −1.760912591

But this number is not the SNR Sampling show by the sh controllers dsl 0 !!

Exist an OID to match this one ?

Could you explain us the difference between this 2 SNR ?

Could you give us the way to calcul the SNR Sampling from snmp values ? (like Transnit power and receiver gain, or don't know).

Best regards.

PD:

For a adsl router like the 877 or the 857 the snmp value (/10) and the sh dsl interface is the same.

877adsl#sh dsl interface
Capacity Used:   46%                             100%
Noise Margin:    23.5 dB                         22.0 dB
Output Power:    20.5 dBm                         6.0 dBm
Attenuation:     21.0 dB                          4.0 dB

Noise margin download:

vincent@sistemes-vincent:~$ snmpwalk -c public -v1 x.x.x.x .1.3.6.1.2.1.10.94.1.1.3.1.4
SNMPv2-SMI::transmission.94.1.1.3.1.4.12 = Gauge32: 230

Noise margin upload:

vincent@sistemes-vincent:~$ snmpwalk -c public -v1 x.x.x.x .1.3.6.1.2.1.10.94.1.1.2.1.4
SNMPv2-SMI::transmission.94.1.1.2.1.4.12 = Gauge32: 220

osgpcqosg · ‎03-28-2011

By the way the oid I use to check the SNR of the 878 router is: hdsl2ShdslEndpointCurrSnrMgn(2) (http://www.oid-info.com/get/1.3.6.1.2.1.10.48.1.5.1.2)

mavespig · ‎03-28-2011

Hi Vincent,

I don't see 1.3.6.1.2.1.10.48 as an available MIB on Cisco SNMP Object Navigator (http://tools.cisco.com/Support/SNMP/do/BrowseOID.do?local=en)

Can you try CISCO-SDSL-LINE-MIB?

For example:

cSdslStucCurrSnrMgn (1.3.6.1.4.1.9.9.155.1.2.1.7)

"This object specifies the SNR margin as seen by this STU-C with respect to its received signal."

http://tools.cisco.com/Support/SNMP/do/BrowseOID.do?local=en&translate=Translate&objectInput=1.3.6.1.4.1.9.9.155.1.2.1.7#oidContent

cSdslSturCurrSnrMgn (1.3.6.1.4.1.9.9.155.1.3.1.7)

"This object specifies the SNR margin as seen by this STU-R with respect to its received signal."

http://tools.cisco.com/Support/SNMP/do/BrowseOID.do?local=en&translate=Translate&objectInput=1.3.6.1.4.1.9.9.155.1.3.1.7#oidContent

Cheers

Marco

osgpcqosg · ‎03-30-2011

Thanks for you reply but seems not working:

~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.2.1.10.48.1.5.1.2.10.2.1.1
SNMPv2-SMI::transmission.48.1.5.1.2.10.2.1.1 = INTEGER: 17
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx 1.3.6.1.4.1.9.9.155.1.2.1.7
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx 1.3.6.1.4.1.9.9.155.1.2.1
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx 1.3.6.1.4.1.9.9.155.1.2
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx 1.3.6.1.4.1.9.9.155.1
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx 1.3.6.1.4.1.9.9.155
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.4.1.9.9.155
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.4.1.9.9.155.1.3.1.7
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.4.1.9.9.155.1.3.1
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.4.1.9.9.155.1.3
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.4.1.9.9.155.1
~# snmpwalk -c lmt -v 1 xxx.xxx.xxx.xxx .1.3.6.1.4.1.9.9

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SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.1 = STRING: "CW_BEGIN$-gs-advsecurityk9-m$"
SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.2 = STRING: "CW_IMAGE$C870-ADVSECURITYK9-M$"
SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.3 = STRING: "CW_FAMILY$C870$"
SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.4 = STRING: "CW_FEATURE$IP|FIREWALL|3DES|IPSEC$"
SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.5 = STRING: "CW_VERSION$12.4(24)T4$"
SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.6 = STRING: "CW_MEDIA$RAM$"
SNMPv2-SMI::enterprises.9.9.25.1.1.1.2.7 = STRING: "CW_SYSDESCR$Cisco IOS Software, C870 Software (C870-ADVSECURITYK9-M), Version 12.4(24)T4, RELEASE SOFTWARE (fc2)

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osgpcqosg · ‎08-09-2011

Still looking for this, anybody have a solution for this ?

osgpcqosg · ‎02-28-2012

Correct calcul: 10 log (13.5/9) = 1.760912591

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