Cisco 867 stops responding to SNMP every 6 hours

[caseyandrew]

Bit of an odd one, I have a Cisco 867 running at home, managed via SNMP and observium.  Every 6 hours, it stops responding to SNMP requests for around 20 minutes, then it goes back to normal.  The network continues to work correctly through that time, it's just SNMP.

I've tried a different SNMP manager, same thing happens.  Plus other devices and a cisco router (1841) continues to respond during the time the modem doesn't.

Here's the config of the modem: https://pastebin.com/u0DTr6vw

and what the dropouts look like: https://imgur.com/a/iiNrdN7

Any help would be nice... it's not urgent, just one of those things that would be nice to get to the bottom of.

[Leo Laohoo]

Try a different IOS.

[caseyandrew]

Would love to try a different IOS, but don't know where to download them from.  Cisco keeps saying something about a contract... I got this modem from my ISP, I don't think i'm still in contract with them.

[balaji.bandi]

I do not see any issue here, To dianosis the issue -  when the SNMP Stop can you run SNMPwalk and see did the device responds ? 

[caseyandrew]

Finally managed to catch it while it was down.

SNMPwalk shows not responding.

turned debug on:

SNMP:
SNMP Detail debugging is on
SNMP packet debugging is on

SNMP:
SNMP MGR requests debugging is on

Nothing at all shows up.  Even when I manually snmpwalk again.  It's like it just closes the port.

Infact, I did a port scan on it:

PORT STATE SERVICE REASON
162/udp open|filtered snmptrap no-response

[Georg Pauwen]

Hello,

in addition to the other posts, there are a few parameters you could adjust:

snmp-server manager session-timeout

--> the default is 10 minutes, set it to the highest availabe value

Also, try and configure a simple SLA that pings your SNMP server constantly (192.168.1.1 would be the IP address of your SNMP server, change that to the IP address that applies to your topology):

ip sla 1
icmp-echo 192.168.1.1 source-ip 192.168.1.254
frequency 300
timeout 2000

!

ip sla schedule 1 life forever start-time now

[caseyandrew]

I've added the timeout and SLA, but no change sorry.

Thanks for the idea.

[Georg Pauwen]

Hello,

what are you running Observium on, Linux ? If so, can you post the snmpd.config file ?

[caseyandrew]

$ sudo cat /etc/snmp/snmpd.conf
agentAddress udp:127.0.0.1:161
rocommunity [redacted]
extend .1.3.6.1.4.1.2021.7890.1 distro /usr/bin/distro

It's nothing special, default config.

It's also polling a Cisco 1841 which is doing my VLAN routing with no breaks at all.

[Georg Pauwen]

Hello,

so I assume when the 867 does not respond to the snmpwalk, the 1841 does ? That would exclude trying to restart the SNMP daemon...

One thing you could try is configure a different SNMP version (v3) on the 867:

snmp-server group 867RO v3

You would need to add a line to your snmpd.config for that...

[caseyandrew]

Thanks for the suggestion (and thanks for all your help up till now)... Tried v3 quickly, but kept getting invalid engine ID and invalid username when using snmpwalk.  

Need to look into it a bit further.