I'm having a hard time with my DELL 6224 switch.

This switch is the center node of my network, trunking between other switches, VLANs and routing packets.

The network traffic that it's been handled is pretty low, about 20% of its total capacity. However it's presenting a strange behaviour.




S=Dell 6224


When I ping A->B or B->A everything works flawlessly. But when I ping A->S or B->S, no matter what VLANs, the switch does not respond to the pings requests as it was supposed to do. Some ping replys have high latencies times and timeouts, like if it was suffering from overload traffic or if it's not prioritizing ICMP traffic directed to it.

Is this behaviour normal? Doesn't seems to be, at least for me.

Thanks in advance!


CPU Utilization:

 PID     Name                     5 Sec    1 Min    5 Min
 336d060 tTffsPTask               0.00%    0.02%    0.00%
 3383e90 tNetTask                 0.63%    0.52%    0.34%
 3570370 ipnetd                   0.00%    0.02%    0.15%
 3582910 tXbdService              0.31%    1.38%    1.91%
 359d950 osapiTimer               0.79%    0.98%    1.09%
 368ef20 bcmL2X.0                 0.00%    0.26%    0.13%
 36a4500 bcmCNTR.0                0.00%    0.26%    0.37%
 36d75e0 bcmTX                    0.15%    0.18%    0.30%
 3cce7e0 bcmRX                    0.47%    0.66%    0.77%
 3cee9d0 bcmNHOP                  0.00%    0.02%    0.00%
 3f04a10 MAC Send Task            0.31%    0.19%    0.15%
 3f0df10 MAC Age Task             0.00%    0.05%    0.02%
 4a8e580 bcmLINK.0                0.47%    0.36%    0.28%
 4d18a10 LOG                      0.00%    0.06%    0.01%
 518f860 tL7Timer0                0.00%    0.04%    0.00%
 51b5140 osapiMonTask             0.00%    0.00%    0.08%
 5ea3d40 simPts_task              0.00%    0.12%    0.17%
 61b4ea0 UtilTask                 0.00%    0.02%    0.00%
 62d8100 dtlTask                  0.31%    0.59%    0.67%
 63398b0 tEmWeb                   0.31%    0.15%    0.06%
 6369e50 hapiRxTask               0.79%    0.31%    0.31%
 698be00 DHCP snoop               0.15%    0.04%    0.00%
 6a20eb0 Dynamic ARP Inspection   0.00%    0.05%    0.00%
 76602f0 dot1s_timer_task         0.47%    0.55%    0.62%
 849a550 unitMgrTask              0.00%    0.02%    0.00%
 863b200 snoopTask                0.00%    0.06%    0.00%
 8670640 dot3ad_timer_task        0.00%    0.02%    0.15%
 95f1690 ipMapForwardingTask      1.27%    4.90%    6.04%
 96bc9a0 tRipTask                 0.00%    0.02%    0.00%
 9aef570 IpHelperTask             0.00%    0.00%    0.01%
 9b01760 tRtrDiscProcessingTask   0.00%    0.02%    0.00%
 ca57310 voipTask                 0.47%    0.52%    0.61%
 cbe0860 lldpTask                 0.79%    0.49%    0.61%
 d838170 isdpTask                 0.00%    0.04%    0.01%
 e039950 RMONTask                 0.15%    0.10%    0.15%
 e045ff0 boxs Req                 0.15%    0.08%    0.00%
 Total CPU Utilization            7.99%   13.10%   15.01%

I'm using a number of them as layer 3 entities in a network w/ around 2,000 hosts and that's not normal behavior for that switch. It does sound like how that switch would act if you're using the spanning tree protocol (STP) and the topology is thrashing. The 6200-series, in my opinion, handles STP topology changes poorly, in terms of the layer 3 performance during the topology change.

The best place to look, right now, would be the show process cpu output and the switch's log. Have a look there, see what you've got, and update your question and we'll get to the bottom of the issue.


Whoa there. I didn't read your question very well. Sorry about that!

I regularly see high latency in ICMP echoes to the management and routing interfaces on 6200-series switches. They've acted that for me through every firmware revision I've ever used. The routing engine doesn't seem to drop packets when the PINGs to the switch get cruddy (and they definitely get cruddy when the STP topology changes, but CPU usage goes through the roof at that time, too).

  • Thanks Evan for the response. Look at the CPU utilization, it's pretty low. About the STP setting, it's turned off on all switches. – gmuller Feb 7 '12 at 18:39
  • I dropped on an edit. – Evan Anderson Feb 7 '12 at 19:17

I've found the problem!

There were two things. For the solution, first I enabled spanning tree on all switches with the RSTP setting. All ports conected to edge devices, like computers printers and etc, where set to PORT FAST setting. The problem got softier, but then I realized that all my ports/port channels were set with the option: "switchport voice detect". I think this option, puts some unnecessary processing on the hardware and the switch passes all processing (routing and traffic) to the firmware, leaving the switch unstable. Turning that setting of on all ports resolved the problem for good! Now the 6224 is rocking solid with low cpu usage and responding to every ping I sent to him! =)

  • What firmware version are you on? – Evan Anderson Mar 2 '12 at 17:31

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