[c-nsp] Router down - What is "Net Background"?

[Christian]

the net background proess. sends interface keepalive packets and processes
interface state changes

On Fri, Apr 4, 2008 at 10:42 AM, Justin Shore <justin at justinshore.com>
wrote:

> I just had a 3660 terminating about 1500 PVCs for DSL die this AM.  The
> 3660 is running 12.3(22) w/ 256MB of RAM.  I'm at the remote POP now,
> consoled in and looking at the box.  The console hangs for 45-60s before
> I get a chance to run a quick command or two.  Then it goes back to the
> hung state about 5 seconds later.  The box keeps dropping my 2 OC3s and
> bouncing my IS-IS processes.  Syslog didn't appear to capture anything
> interesting leading up to this crash.  I had the box power cycled while
> I was driving down here.
>
> Overall the CPU is low and neither CPU nor memory were being taxed over
> the past number of months.  The Net Background process is using a fair
> bit of the processor.  Actually, that's an understatement.  At times
> it's only using 9% or so.  At other times it's up to 97% as was the case
> here:
>
> 3660-2.brd#sh proc cpu sort 5m
> CPU utilization for five seconds: 1%/0%; one minute: 17%; five minutes:
> 19%
>  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process
>   28     4715940       611    7731049 97.09% 13.74%  9.23%   0 Net
> Background
>   31      238608       865     275847  2.65%  8.58%  8.48%   0
> Per-Second Jobs
>    5        8336       684      12187  0.00%  0.56%  0.68%   0 Check
> heaps
>   60        7764      7776        998  0.01%  0.27%  0.43%   0 IP Input
>
>   18        3856      8741        441  0.00%  0.42%  0.33%   0 ARP
> Input
>  167        2556      3046        839  0.02%  0.12%  0.13%   0 ISIS Upd
>
>  140        2732        15     182133  0.00%  0.00%  0.12%   0 Key Proc
>
>  179        1680      1676       1002  0.00%  0.13%  0.11%   0 OSPF
> Router
>   47        1912       152      12578  0.00%  0.12%  0.11%   0
> Per-minute Jobs
>   82        1792       597       3001  0.01%  0.15%  0.11%   0 IP
> Background
>    3        1828       238       7680  0.00%  0.11%  0.09%   0 OSPF
> Hello
>  100         644      1217        529  0.00%  0.13%  0.08%   0 DHCPD
> Receive
>   51        1700       376       4521  0.00%  0.04%  0.05%   0 ATM
> Periodic
>   83         700       417       1678  0.00%  0.01%  0.02%   0 IP RIB
> Update
>  108         500       871        574  0.00%  0.06%  0.02%   0 CEF
> process
>  124         172       471        365  0.00%  0.04%  0.02%   0 Exec
>
>  166         620      1908        324  0.00%  0.03%  0.02%   0 ISIS Adj
>
>  106         420       284       1478  0.00%  0.03%  0.00%   0 Adj
> Manager
>    6         436      1406        310  0.00%  0.02%  0.00%   0 Pool
> Manager
>   91         188       556        338  0.00%  0.01%  0.00%   0 ILMI
> Timer Proce
>  163          92      1795         51  0.00%  0.00%  0.00%   0 CLNS
> Input
>
>
> Per-Second Jobs is also using quite a bit of CPU.  The log has CPUHOG
> entries in it pointing at the Net Background process too:
>
> 000428: .Apr  4 08:36:31 CDT: %SYS-3-CPUHOG: Task ran for 50332 msec
> (10/0), process = Net Background, PC = 60439FFC.
> -Traceback= 6043A004
>
> What does the Net Background process do?  I haven't been able to find
> any answers on Cisco.com.
>
>
> We're in the middle of SmartNet renewals and negotiations and
> unfortunately this box's contract has expired.  I can have our AM bless
> a TAC case for us if need be, assuming I can locate him; I think he's in
> training this week back East.
>
> Any ideas?  I'm going to go back and scrutinize the log for anything
> useful.  As of right now the box is intermittently pingable,
> corresponding directly to the brief instances that I can use the
> console.  Customer packets seem to flow about as well.
>
> Thanks
>  Justin
>
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