[e-nsp] Extreme Networks Summit1iTx L3 switch delays ICMP traffic routed through the switch or addressed to the switch

[Shankar]

ICMP traffic is always software forwarded in EWare....so the RTT is higher
when compared to other traffic that is hardware forwarded....

Regards,
Shankar
On 25 Aug 2014 20:56, "Martin T" <m4rtntns at gmail.com> wrote:

> Hi,
>
> I have a legacy Extreme Networks Summit1iTx L3 switch(running EW
> 7.8.4.1), which delays ICMP traffic routed through the switch and ICMP
> traffic addressed to the switch while traffic switched through the
> switch is not affected. For an odd reason, only ICMP traffic seems to
> be affected and not for example TCP or UDP traffic. There is a clear
> correlation between high RTT and low CPU utilization(less than 90%) of
> tBGTask process. It is always the tNetTask process, which CPU usage
> increased and thus forced tBGTask process utilization below 90%.
> According to ExtremeWare 7.0 software manual, tNetTask(network stack
> task) process is responsible for handling all the software-based
> processing of packets including:
>
> 1) Packets that cannot be handled by the switch's ASIC because the
> forwarding tables do not have entries built in.
> 2) Packets destined to the CPU for one of the router interfaces.
> 3) Packets that must be examined or snooped by the CPUPackets detected
> for copying to the CPU.
>
> Has anyone seen such behavior before? Why does low CPU utilization of
> tBGTask process affect only ICMP traffic? Any suggestions how to see
> exactly which traffic causes CPU utilization of tNetTask process to
> increase?
>
>
>
> thanks,
> Martin
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