[c-nsp] Ping TO Gateway is High Latency, Ping THROUGH Gateway is Normal Latency

[Mack O'Brian]

When you ping to the router it has to go to the CPU for processing and
depending upon how busy the router is you will get lower priority on the
pings. But if you ping through the router to some where else then that is a
forwarding plane and it may be hardware switched which will not be punted to
the cpu. It seems your cpu is busy.


On Mon, Oct 18, 2010 at 10:50 AM, Felix Nkansah <felixnkansah at gmail.com>wrote:

> Hi,
>
> I am noticing what I think is a strange behavior.
>
> I have a Cisco ISR Internet gateway that is also performing
> router-on-a-stick for the Internal network.
>
> From a PC in one VLAN when I ping another resource in other VLANs, the ping
> latency is normal (<2ms).
>
> When I ping resources on the Internet, the ping latency is also normal
> (<170ms).
>
> However, when I ping the router interface IP itself (default gateway), the
> latency is extremely high (>450ms).
>
> Even though traffic THROUGH the router has a normal response time, I am
> wondering why traffic TO the router results in high latency.
>
> Meantime if I ping internal resources from the router itself, I get <1ms
> response time.
>
> I would appreciate an explanation from other members.
>
> Thanks. Felix
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