Vanished MAC in Arris CM820""B"" ? | docsis.org

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Vanished MAC in Arris CM820""B"" ?

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hinzoo
Vanished MAC in Arris CM820""B"" ?

Hi!

I just got a bunch of CM820B modems. There is an interesting thing about those. I used to read by snmp an address from the CM's using:

snmpwalk -v1 -c community 10.130.0.123 .1.3.6.1.2.1.17.4.3.1 and I have always got smth like that:
(any modem, any vendor)

SNMPv2-SMI::mib-2.17.4.3.1.1.32.229.42.88.81.233 = STRING: " �*XQ�"
SNMPv2-SMI::mib-2.17.4.3.1.1.232.137.44.177.33.180 = Hex-STRING: E8 89 2C B1 21 B4
SNMPv2-SMI::mib-2.17.4.3.1.1.232.137.44.177.33.181 = Hex-STRING: E8 89 2C B1 21 B5
SNMPv2-SMI::mib-2.17.4.3.1.2.32.229.42.88.81.233 = INTEGER: 1
SNMPv2-SMI::mib-2.17.4.3.1.2.232.137.44.177.33.180 = INTEGER: 1
SNMPv2-SMI::mib-2.17.4.3.1.2.232.137.44.177.33.181 = INTEGER: 2
SNMPv2-SMI::mib-2.17.4.3.1.3.32.229.42.88.81.233 = INTEGER: 3
SNMPv2-SMI::mib-2.17.4.3.1.3.232.137.44.177.33.180 = INTEGER: 4
SNMPv2-SMI::mib-2.17.4.3.1.3.232.137.44.177.33.181 = INTEGER: 4

Now, with CM820B's i got just that:

SNMPv2-SMI::mib-2.17.4.3.1.1.0.35.105.171.134.129 = Hex-STRING: 00 23 69 AB 86 81
SNMPv2-SMI::mib-2.17.4.3.1.1.232.62.252.93.188.34 = STRING: "�>�]�\""
SNMPv2-SMI::mib-2.17.4.3.1.1.232.62.252.93.188.35 = STRING: "�>�]�#"
SNMPv2-SMI::mib-2.17.4.3.1.2.0.35.105.171.134.129 = INTEGER: 1
SNMPv2-SMI::mib-2.17.4.3.1.2.232.62.252.93.188.34 = INTEGER: 1
SNMPv2-SMI::mib-2.17.4.3.1.2.232.62.252.93.188.35 = INTEGER: 2
SNMPv2-SMI::mib-2.17.4.3.1.3.0.35.105.171.134.129 = INTEGER: 3
SNMPv2-SMI::mib-2.17.4.3.1.3.232.62.252.93.188.34 = INTEGER: 4
SNMPv2-SMI::mib-2.17.4.3.1.3.232.62.252.93.188.35 = INTEGER: 4

Please anybody could confirm that? Am I wrong? Or it is just another Arris bananaware improvement?

kwesibrunee
this is why it is important

this is why it is important to install the mibs if you are going to use them

output on my end shows
BRIDGE-MIB::dot1dTpFdbAddress.'.@.3A]' = STRING: 0:40:ca:33:41:5d
BRIDGE-MIB::dot1dTpFdbAddress.'......' = STRING: 14:cf:e2:1c:15:a
BRIDGE-MIB::dot1dTpFdbAddress.'......' = STRING: 14:cf:e2:1c:15:b
BRIDGE-MIB::dot1dTpFdbPort.'.@.3A]' = INTEGER: 1
BRIDGE-MIB::dot1dTpFdbPort.'......' = INTEGER: 1
BRIDGE-MIB::dot1dTpFdbPort.'......' = INTEGER: 2
BRIDGE-MIB::dot1dTpFdbStatus.'.@.3A]' = INTEGER: learned(3)
BRIDGE-MIB::dot1dTpFdbStatus.'......' = INTEGER: self(4)
BRIDGE-MIB::dot1dTpFdbStatus.'......' = INTEGER: self(4)

if you add the bridge-mib to your known mibs you will get output similar to this.

the reason you are getting garbly gook is because without the mib net-snmp tries to guess whether it is hex data as a string or an ascii string and as you found it is less than ideal. However with the mib installed it knows it's a string and even formats it as a mac address for you.

Though I expect that you want Hex-STRING: 00 23 69 AB 86 81 type output, you can force that without installing the mib by passing the -Ox option to the snmpcmd. It won't do anything if you have the mib installed.

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