Re: Cisco ASR9902 SNMP polling ... is interesting

[Saku Ytti via NANOG <nanog () lists nanog org>]

On Sun, 3 Aug 2025 at 16:40, Tom Beecher via NANOG
<nanog () lists nanog org> wrote:

> When you say 'the control plane receives 100% of the packets', it sort of
> depends on what you define as the 'control plane'. That's usually defined
> as 'did the packet get to the RE/RP to process it' There are many scenarios
> by which this can break :
>
>    - Interface buffers may be full
>    - Interface buffers may be drained fast enough
>    - Oversubscription of forwarding complex
>    - Poorly designed QoS
>    - Incorrect config/bugs of control plane policer on internal interface
>    to CP switch
>    - Central CPU (RE, RP, etc) overwhelmed
>    - Internal CP switch malfunctioning


Goot starting point is:

RP/0/RSP0/CPU0:leruuter#show lpts pifib hardware police location
0/3/CPU0 | i SNMP
SNMP                   25      Static  300        300        0
           0                    01234567
RP/0/RSP0/CPU0:leruuter#show snmp request drop summary
NMS Address          INQ   Encode    Duplicate   Stack    AIPC
Overload   Timeout   Internal    Threshold
 192.0.2.1            0       0        0          0        0       0
     4          0      0
 192.0.2.2            0       0        0          0        0       0
     2          0      0


Further 'show snmp trace ...' will help.

But this gets really tricky, really fast, you really need your account
team on your side.

-- 
  ++ytti
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